How string. How to String a Guitar: Expert Guide for Perfect Tuning and Longevity

How to change guitar strings properly. When should you replace guitar strings. What tools are needed for restringing a guitar. How to remove old strings safely. How to install new strings correctly. How to tune and stretch new guitar strings. How to maintain guitar strings for optimal performance.

The Importance of Proper Guitar Stringing

Properly stringing a guitar is a crucial skill for any guitarist, from beginners to seasoned professionals. Many players underestimate the impact that correct string installation can have on their instrument’s performance and playability. Poor stringing techniques can lead to frequent tuning issues, premature string breakage, and an overall diminished playing experience.

Why is it so important to master this skill? A well-strung guitar offers:

• Improved tuning stability
• Better intonation
• Longer string life
• Enhanced playability
• Consistent tone quality

In this comprehensive guide, we’ll walk you through the process of stringing a guitar like a pro, ensuring that you can maintain your instrument in top condition and focus on what really matters – making great music.

When to Change Your Guitar Strings

Knowing when to change your guitar strings is as important as knowing how to change them. But how can you tell it’s time for a string change?

Visual indicators are often the most reliable. Inspect your strings closely, paying attention to:

• Visible dirt or grime accumulation
• Signs of rust or corrosion
• Discoloration or dullness
• Visible wear or fraying, especially in playing areas

Beyond visual cues, you may notice changes in your guitar’s sound or playability:

• Difficulty staying in tune
• Loss of brightness or clarity in tone
• Decreased sustain
• Rough or uncomfortable feel when playing

As a general rule, consider changing your strings once a month if you play regularly. For heavy players or those who perform frequently, changing strings every two weeks may be necessary to maintain optimal sound quality and playability.

Essential Tools for Guitar Restringing

Before diving into the restringing process, it’s crucial to gather the necessary tools. Having the right equipment on hand will make the job easier and help prevent damage to your guitar. Here’s what you’ll need:

1. A new set of guitar strings
2. String cutter or wire cutters
3. String winder (manual or electric)
4. Clean cloth for wiping down the guitar
5. Flat surface to work on
6. Optional: neck support or guitar stand

When selecting new strings, consider factors such as string gauge, material, and coating. If you’re new to restringing, opt for a light-gauge set to minimize the risk of accidental breakage during installation.

Choosing the Right Strings

The choice of strings can significantly impact your guitar’s tone and playability. Consider these factors when selecting strings:

• Gauge: Lighter gauges are easier on the fingers but may produce less volume, while heavier gauges offer more sustain and volume but require more finger strength.
• Material: Common options include nickel-plated steel, pure nickel, stainless steel, and bronze (for acoustic guitars).
• Coating: Some strings feature special coatings that can extend their lifespan and reduce finger noise.

Experiment with different types to find the strings that best suit your playing style and tonal preferences.

Step-by-Step Guide to Removing Old Strings

Removing old strings is the first step in the restringing process. Follow these steps to safely and effectively remove your old strings:

1. Loosen the tension: Starting with the high E string (the thinnest), use your string winder to loosen each string until it’s completely slack. Work your way down to the low E string.
2. Cut the strings: Once all strings are loose, use your string cutter to snip each string near the middle of the guitar body. This makes removal easier and safer.
3. Remove bridge pins (for acoustic guitars): If your guitar has bridge pins, use the notched end of your string winder to carefully pull them out. Always pull straight up to avoid damaging the pins or the bridge.
4. Unwrap and remove strings from the tuning pegs: Carefully unwind each string from its tuning peg and pull it through the bridge or tailpiece.
5. Dispose of old strings safely: Coil the old strings together to prevent them from becoming a safety hazard.

Remember to exercise caution when handling old strings, as the cut ends can be sharp.

Preparing Your Guitar for New Strings

With the old strings removed, you have a perfect opportunity to clean and inspect your guitar. This step is often overlooked but can significantly improve your instrument’s performance and longevity.

Cleaning the Fretboard

A clean fretboard not only looks better but can also enhance playability. How should you clean your fretboard?

• Use a soft, lint-free cloth to remove dust and debris.
• For stubborn dirt, lightly dampen the cloth with water or a specialized fretboard cleaner.
• Gently scrub between the frets, being careful not to oversaturate the wood.
• For unfinished fretboards (like rosewood or ebony), consider applying a small amount of lemon oil or specialized fretboard conditioner to prevent drying and cracking.

Inspecting the Guitar

Take this opportunity to inspect your guitar for any issues that may need attention:

• Check for loose or protruding frets
• Inspect the nut and bridge for wear or damage
• Look for any cracks or separation in the wood
• Ensure all hardware (tuning machines, bridge, etc.) is secure

Addressing any issues now can prevent more serious problems down the line and ensure your newly strung guitar performs at its best.

Installing New Strings: A Detailed Walkthrough

Now that your guitar is clean and ready, it’s time to install the new strings. This process requires patience and attention to detail, but with practice, it becomes second nature.

Step 1: Inserting the Strings

For acoustic guitars:

1. Insert the ball end of each string into its corresponding hole in the bridge.
2. Secure each string with its bridge pin, ensuring the groove in the pin aligns with the string.

For electric guitars:

1. Thread each string through its corresponding hole in the bridge or tailpiece.
2. For guitars with string-through bodies, feed the strings through the back of the guitar body.

Step 2: Attaching Strings to Tuning Pegs

Proper attachment to the tuning pegs is crucial for tuning stability. Follow these steps:

1. Pull the string taut and measure about 2-3 inches (5-7.5 cm) past its corresponding tuning peg.
2. Make a 90-degree bend in the string at this point.
3. Insert the string through the hole in the tuning peg.
4. Wind the string around the peg, ensuring each wrap goes below the previous one.
5. Aim for 2-3 neat wraps around the peg for optimal stability.

Step 3: Tuning and Stretching

Once all strings are attached, it’s time to bring them up to pitch:

1. Using a tuner, bring each string roughly up to pitch.
2. Gently stretch each string by pulling it away from the fretboard at various points.
3. Retune the strings, as stretching will cause them to go flat.
4. Repeat the stretching and tuning process several times until the strings hold their pitch.

This stretching process helps the strings settle into their new tension more quickly, reducing the need for frequent retuning in the first few days after changing strings.

Troubleshooting Common Stringing Issues

Even with careful attention, you might encounter some issues when stringing your guitar. Here are some common problems and their solutions:

Strings Slipping Out of Tune

If your strings won’t stay in tune, consider these potential causes:

• Insufficient wraps around the tuning peg
• Improper string stretching
• Worn or improperly cut nut slots

Solution: Ensure you have 2-3 neat wraps around each tuning peg and thoroughly stretch new strings. If problems persist, consider having a professional check your guitar’s nut.

String Breakage

Frequent string breakage can be frustrating. Common causes include:

• Sharp edges on bridge saddles or nut slots
• Overly tight string windings
• Excessive bending or aggressive playing style

Solution: Inspect your guitar’s bridge and nut for sharp edges. If found, carefully file them down or seek professional help. Ensure your string windings are neat but not overly tight.

Buzzing Strings

String buzz can be caused by:

• Low action (string height)
• Uneven frets
• Improper neck relief

Solution: While some of these issues require professional setup, you can try slightly raising your guitar’s action if you’re comfortable doing so. If problems persist, consult a guitar technician.

Maintaining Your Newly Strung Guitar

Proper maintenance can extend the life of your strings and keep your guitar playing its best. Here are some tips for maintaining your newly strung guitar:

Regular Cleaning

Clean your strings after each playing session:

• Use a soft, dry cloth to wipe down the strings, removing oils and sweat.
• For deeper cleaning, use a specialized string cleaner product.

Proper Storage

How you store your guitar can significantly impact string life:

• Store your guitar in a case when not in use to protect it from dust and humidity changes.
• Use a humidifier in dry climates to prevent wood shrinkage and potential fret issues.

Regular Inspections

Periodically check your guitar for signs of wear or needed adjustments:

• Look for signs of corrosion or discoloration on the strings.
• Check the action and intonation, adjusting as necessary.
• Inspect the frets for wear and the neck for proper relief.

By following these maintenance tips, you can ensure that your newly strung guitar continues to play and sound its best for as long as possible.

Advanced Stringing Techniques for Different Guitar Types

While the basic principles of stringing remain consistent across guitar types, certain instruments may require specific techniques. Let’s explore some advanced stringing methods for different guitar styles:

Classical Guitars

Classical guitars use nylon strings and have a unique tying method at the bridge:

1. Thread the string through the bridge hole from the top.
2. Create a loop by bringing the string back up and under itself.
3. Wrap the string around itself 2-3 times, then pull tight.
4. Trim excess string, leaving about 1/4 inch (6mm).

Floyd Rose-Equipped Electric Guitars

Guitars with Floyd Rose tremolo systems require a specific stringing process:

1. Remove the locking nut plates at the headstock.
2. Loosen the string lock screws on the bridge.
3. Thread strings through the bridge as usual, but clip them short at the tuning pegs.
4. Tighten string lock screws at the bridge.
5. Tune to pitch, then re-lock the nut plates.

12-String Guitars

Stringing a 12-string guitar follows the same principles as a 6-string, but with some considerations:

• String in pairs, with the thinner octave string on top for the four lower pairs.
• The high B and E strings are doubled in unison, not octaves.
• Take extra care to ensure even tension across each pair of strings.

Mastering these advanced techniques will allow you to maintain a wider variety of guitars effectively.

By following this comprehensive guide, you’ll be able to string your guitar like a professional, ensuring optimal performance and longevity for your instrument. Remember, practice makes perfect – the more you change your strings, the more comfortable and efficient you’ll become with the process. Happy stringing!

How to String a Guitar [The Best Way to Change Strings!]

So many people screw up when learning how to string a guitar.

Guitarists might think they know how to string a guitar, but chances are they haven’t learned the proper way.

They’ll say, “I’ll just wrap the strings around the tuning machines and it’ll work.”

If only it were that easy…

If you’re looking to have fun while playing the guitar, you need to set yourself up for success.

Otherwise, you’re going to be out of tune constantly, breaking strings, and seriously not having fun…and I don’t want that happening.

Today, I’m going to show you how to string a guitar like a pro. It’s a method that will guarantee your strings won’t slip out of tune as much and won’t lead to any unnecessary broken strings.

Have more fun on guitar: Request an invite to learn proven methods that will improve your guitar practice habit.

Keep reading to learn how to string a guitar like a pro…

Why Should You Change Guitar Strings?

Guitar strings, like most things in life, wear out over time.

When you can see dirt, rust, or “funk” on your strings…it’s time to change your strings.

If you look closely in the picture above, you can see the dirt on the string — especially on the 1st fret area.

As a rule of thumb, change your guitar strings once a month. If you play frequently and for long periods of time, consider changing your strings every two weeks.

What Do You Need to String a Guitar?

• Guitar
• Pack of strings
• String cutter
• String winder
• Flat surface
• Your favorite record/album (for listening, of course)
• A soothing beverage (be it water, whiskey, coffee, or tea)

As far as picking the right set of strings, that’s a whole other issue you can read about here.

For learning how to string a guitar, I’d use a light-gauge string that doesn’t cost too much — just in case you accidentally break a string while putting it on!

Step 1: Loosen the Strings

Start at the high E string (the thinnest string). Use your string winder to loosen the tension on the string.

• If you aren’t sure which way to turn the tuner, try plucking the note and turning.
• If the note gets higher in pitch, you’re going the wrong way!

Working from the high E string down to the low E string, loosen each string until all six strings are slack and resting on the frets.

Step 2: Cut the Strings

If you have any pent-up anger, nows the time to get it out…

Use your string cutters to snip each string just above the soundhole.

• Cut the strings above the soundhole so your hardware doesn’t scratch the finish on your guitar!
• Cut the strings one at a time so you can savor the moment…it’s not every day you get to cut guitar strings!

Step 3: Remove the Strings

When learning how to string a guitar on your steel-string acoustic guitar, you’re most likely going to have bridge pins that hold the strings in place.

Bridge pins are the little pegs on the bridge of your guitar.

Use your string winder to remove the bridge pins.

• Most string winders have a notch in them that can safely remove the bridge pins without hurting the guitar.

When you have the bridge pin secure in the notch of the string winder, pull straight up.

DO NOT pull on the bridge pins at an angle! This will most likely snap the bridge pins.

As you remove the ball-end of the strings from the bridge, make sure to put the bridge pin back in its hole — that way you don’t have any missing bridge pins.

The next part of learning how to string your guitar involves removing the strings from the headstock (where the tuning machines are).

Caution: the tips of the strings are sharp, so make sure you don’t accidentally stab yourself!

• One safe way to manage all these strings is to coil them around each other so they don’t stab you or an innocent bystander!

Optional Step: Clean the Guitar

Once all the strings are off of the guitar, you have the opportunity to clean tough-to-reach spots.

For some of you, you won’t need to do this. But as a good habit, I always like to run a clean cloth across the fretboard, headstock, and near the bridge.

• These places like to accumulate dust, so it’s always nice to clean them when you have the chance!

Once you’ve cleaned those spots, let’s get back to learning how to string a guitar!

Step 4: Assemble the NEW Strings

Every package of strings has a different naming convention to help identify which string is which. Make sure to read the packaging to learn that convention.

If there isn’t a way to identify the strings, just look at the numbers on the packaging: the higher the number, the thicker the string.

If you’re looking for recommendations on strings, just know that this is the cheapest way to experiment with your guitar’s tone.

Packs of strings can be dirt cheap, or wildly expensive…but almost always strings are cheaper than a new guitar.

Once you find the low E string, open the packaging away from your face.

If you aren’t careful, the string can uncoil and accidentally stab you in the face…I don’t want that.

Uncoil the strings and lay them out on your work surface.

Step 5: String Your Guitar!

Take your low E string, and hold the ball-end against the bridge pin to create a little bend in the string (as seen in the picture above).

• This will help the ball end sit against the bridge plate inside the guitar — total pro move!

From there, place the ball-end of the string into the hole where the low E string goes.

Finally, press the bridge pin inside the hole to secure the string.

• It might be a little sticky, so don’t be scared to use some pressure.
• Alternatively, if it’s taking too much force to press the bridge pin in, take it out and try it again.

Repeat this process for all of the strings.

At the end of this step, your guitar should look something like this:

Step 6: Thread and Secure Strings

You’ve completed 50% of the tonal transformation that happens when you string a guitar with new strings.

This next part, the final 50%, leads to endless debate amongst guitarists.

• How do you thread and wind the strings on the tuner posts?

I’m going to show you a popular way that works for almost everyone.

Start by using a pencil to lubricate the nut slots (I like to use a carpenter’s pencil because the graphite is nice and soft).

Using the graphite allows the strings to pass through the nut smoothly and will prevent tuning issues once you string your guitar.

You’ll need 20 minutes.

How to string your Guitar at the tuners

1. Pass the low E string through the tuning post

   Pass the pointy end of the string through the hole in the middle of the tuning post.

2. Pull the String Tight, Then Add Slack

   Pull the tail end of the string all the way through the hole in the tuning post. Make sure the string is in the correct nut slot.
   After the string is tight, use your hand near the fretboard to create slack on the tuning post.

3. Start Winding the String

   As you wind, make sure the first revolution of the tuning post goes over the free end of the string. This will ensure the string locks into place.

4. Make Corrections as You String the Guitar

   It’s extremely important that the string first wrap around the tuning post goes over the free end of the string; but, make sure the first wrap doesn’t slip off the top either.

5. Ensure Proper String Winding Direction

   As you turn your tuning peg, make sure the string is winding toward the center of the headstock.

6. Continue Winding the String

   Each successive wind after the first one will go under the tail end of the string toward the headstock.

7. Clip the Tail Ends

   Don’t forget to clip the tail ends off with your string cutters. Try to cut the tail end as close to the tuning post as possible so it doesn’t snag on anything!

8. Stretch and Tune the Strings

   After you’ve learned how to string a guitar, you still have to stretch and tune the strings.
   Place a finger on the 12th fret and give the string a little bend. This will help stretch the string and help it acclimate.

Conclusion

It’s important to change your strings frequently.

When you don’t, your tone can suffer, and you might not have as much fun playing your guitar.

And isn’t that what it’s all about? Having fun and learning an awesome instrument?

Speaking of which, if you’re looking for more ways to have fun on the guitar, I highly recommend that you check out Tony’s Acoustic Challenge.

Now that you have a brand new set of guitar strings, it’s time to break them in. Visit Tony’s Acoustic Challenge to request an invite today.

String Tutorials & Notes | Python

Python String:

Strings are sequences of characters. Your name can be considered a string. Or, say you live in Zambia, then your country name is "Zambia", which is a string.

In this tutorial you will see how strings are treated in Python, the different ways in which strings are represented in Python, and the ways in which you can use strings in your code.

How to create a string and assign it to a variable

To create a string, put the sequence of characters inside either single quotes, double quotes, or triple quotes and then assign it to a variable. You can look into how variables work in Python in the Python variables tutorial.

For example, you can assign a character ‘a’ to a variable single_quote_character. Note that the string is a single character and it is “enclosed” by single quotes.

>>> single_quote_character = 'a'
>>> print(single_quote_character)
a
>>> print(type(single_quote_character)) # check the type of the variable.
<class 'str'>

Similarly, you can assign a single character to a variable double_quote_character. Note that the string is a single character but it is “enclosed” by double quotes.

>>> double_quote_character = "b"
>>> print(double_quote_character)
b
>>> print(type(double_quote_character))
<class 'str'>

Also check out if you can assign a sequence of characters or multiple characters to a variable. You can assign both single quote sequences and double quote sequences.

>>> double_quote_multiple_characters = "aeiou"
>>> single_quote_multiple_characters = 'aeiou'
>>> print(type(double_quote_multiple_characters), type(single_quote_multiple_characters))
<class 'str'> <class 'str'>

Interestingly if you check the equivalence of one to the other using the keyword is, it returns True.

>>> print(double_quote_multiple_characters is double_quote_multiple_characters)
True

Take a look at assignment of strings using triple quotes and check if they belong to the class str as well.

>>> triple_quote_example = """this is a sentence written in triple quotes"""
>>> print(type(triple_quote_example))
<class 'str'>

In the examples above, the function type is used to show the underlying class that the object will belong to. Please note that all the variables that have been initiated with single, double, or triple quotes are taken as string. You can use single and double quotes for a single line of characters. Multiple lines are generally put in triple quotes.

String common methods

2 is returned because the position of the individual letters in the strings is 0-indexed. So, index of “a” in “abcde” is 0, that of “b” is 1, and so on.

• Test if a substring is a member of a larger string. This is done using the keyword in and writing the test. The skeleton is shown below.

  substring in string

  >>> # for example, test if string "i" is present in string "pythonic" at least once. "i" is present in the string. Therefore, the result should be true.
  >>>  "i" in "pythonic"
  True
  >>> # as "x" is not present in the string "pythonic" the below test should return false
  >>> "x" in "pythonic" # "x" is not present in "pythonic"
  False
  

• Join a list of strings using the join method. A list of strings is written by delimiting the sequence with a comma ,, and enclosing the whole group with brackets [...]. For a more detailed tutorial on lists head over to the python lists tutorial.
  You can join a list of strings by giving the delimiter as the object on which the method join will act and the list of strings as the argument.

  >>> # join a list of strings 1, 2, 3 with a space as a delimiter and 1,2,3 as the list of strings.  So, the result will be the strings with spaces between them.
  >>>  combined_string = " ".join(["1", "2", "3"])
  '1 2 3'
  

• Break a string based on some rule.
  This takes in the string as the object on which the method split is passed using the dot operator. Splitting takes a space as the default parameter.

For example you can split a string based on the spaces between the individual values.

    >>> # split the string "1 2 3" and return a list of the numbers.
    >>>  "1 2 3".split() # splitting
    ['1', '2', '3']

Or you can split a string based on a delimiter like :.

     >>> “1:2:3”.split(“:”)
     [‘1’, ‘2’, ‘3’]

Formatting in String:

String object can be formatted. You can use %s as a formatter which will enable you to insert different values into a string at runtime and thus format the string. The %s symbol is replaced by whatever is passed to the string.

    >>>  print("I love %s in %s" % ("programming", "Python")) # templating strings
    'I love programming in Python'

You can also use the keyword format. This will enable you to set your own formatters instead of %s.

>>> print("I love {programming} in {python}".format(programming="programming", python="Python"))
'I love programming in Python'

Truth value testing of String

A string is considered to be true in Python if it is not an empty string. So, we get the following:

# Test truth value of empty string
>>>  print(bool(""))
False

# Test truth value of non-empty string "x"
>>>  print(bool("x"))
True

Contributed by: Joydeep Bhattacharjee

Why String is Immutable or Final in Java? Example

The string is Immutable in Java because String objects are cached in the String pool. Since cached String literals are shared between multiple clients there is always a risk, where one client’s action would affect all another client. For example, if one client changes the value of the String “Test” to “TEST”, all other clients will also see that value as explained in the first example. Since caching of String objects was important from performance reason this risk was avoided by making String class Immutable. At the same time,

so that no one can compromise invariant of String class like Immutability, Caching, hashcode calculation, etc by extending and overriding behaviors. Another reason 

could die due to HashMap.

Since Strings are very popular as the HashMap key, it’s important for them to be immutable so that they can retrieve the value object which was stored in HashMap. Since HashMap works in the principle of hashing, which requires the same has value to function properly. Mutable String would produce two different hashcodes at the time of insertion and retrieval if contents of String were modified after insertion, potentially losing the value object in the map.

If you are an Indian cricket fan, you may be able to correlate with my next sentence. The string is VVS Laxman of Java, i.e. very very special class. I have not seen a single Java program that is written without using String. That’s why a solid understanding of String is very important for a Java developer.

Important and popularity of String as data type, transfer object, and the mediator has also made it popular in Java interviews. Why String is immutable in Java is one of the most frequently asked String Interview questions in Java, which starts with a discussion of,  what is String, how String in Java is different than String in C and C++, and then shifted towards what is an immutable object in Java, what are the benefits of an immutable object, why do you use them and which scenarios should you use them. This question sometimes also asked, “Why String is final in Java”.

On a similar note, if you are preparing for Java interviews, I would suggest you take a look at the Java Programming interview exposed book, an excellent resource for senior and mid-level Java programmers. It contains questions from all important Java topics including multi-threading, collection, GC, JVM internals, and frameworks like Spring and Hibernate, as shown below:

Why String is Final in Java

As I said, there could be many possible answers to this question, and the only designer of String class can answer it with confidence. I was expecting some clue in Joshua Bloch’s Effective Java book, but he also didn’t mention it. I think the following two reasons make a lot of sense on why String class is made immutable or final in Java: 1) Imagine String pool facility without making string immutable, its not possible at all because in case of string pool one string object/literal e.g. “Test” has referenced by many reference variables, so if any one of them change the value others will be automatic gets affected i.e. let’s say

String A = "Test"
String B = "Test"

Now String B called, “Test”.toUpperCase() which change the same object into “TEST”, so A will also be “TEST” which is not desirable. Here is a nice diagram that shows how String literals are created in heap memory and String literal pool.

2. String has been widely used as a parameter for many Java classes e.g. for opening network connection, you can pass hostname and port number as a string, you can pass database URL as a string for opening database connection, you can open any file in Java by passing the name of the file as an argument to File I/O classes.

In case, if String is not immutable, this would lead serious security threat, I mean someone can access to any file for which he has authorization, and then can change the file name either deliberately or accidentally and gain access to that file. Because of immutability, you don’t need to worry about that kind of threats. This reason also gels with, Why String class is final in Java, by making java.lang.String final, Java designer ensured that no one overrides any behavior of String class.

3)Since String is immutable it can safely share between many threads which is very important for multithreaded programming and to avoid any synchronization issues in Java, Immutability also makes String instance thread-safe in Java, means you don’t need to synchronize String operation externally. Another important point to note about String is the memory leak caused by SubString, which is not a thread-related issues but something to be aware of.

4) Another reason of Why String is immutable in Java is to allow String to cache its hashcode, being immutable String in Java caches its hashcode, and do not calculate every time we call hashcode method of String, which makes it very fast as hashmap key to be used in hashmap in Java.  This one is also suggested by  Jaroslav Sedlacek in the comments below. In short because String is immutable, no one can change its contents once created which guarantees hashCode of String to be same on multiple invocations.

5) Another good reason of Why String is immutable in Java suggested by Dan Bergh Johnsson on comments is: The absolutely most important reason that String is immutable is that it is used by the class loading mechanism, and thus have profound and fundamental security aspects. Had String been mutable, a request to load “java. io.Writer” could have been changed to load “mil.vogoon.DiskErasingWriter”

Security and String pool being primary reason of making String immutable, I believe there could be some more very convincing reasons as well, Please post those reasons as comments and I will include those on this post. By the way, above reason holds good to answer, another Java interview question “Why String is final in Java”.  Also to be immutable you have to be final so that your subclass doesn’t break immutability.  what do you guys think?

Further Reading:

The roots and fruits of string theory – CERN Courier

In the summer of 1968, while a visitor in CERN’s theory division, Gabriele Veneziano wrote a paper titled “Construction of a crossing-symmetric, Regge behaved amplitude for linearly-rising trajectories”. He was trying to explain the strong interaction, but his paper wound up marking the beginning of string theory.

What led you to the 1968 paper for which you are most famous?

In the mid-1960s we theorists were stuck in trying to understand the strong interaction. We had an example of a relativistic quantum theory that worked: QED, the theory of interacting electrons and photons, but it looked hopeless to copy that framework for the strong interactions. One reason was the strength of the strong coupling compared to the electromagnetic one. But even more disturbing was that there were so many (and ever growing in number) different species of hadrons that we felt at a loss with field theory – how could we cope with so many different states in a QED-like framework? We now know how to do it and the solution is called quantum chromodynamics (QCD).

Veneziano, photographed at CERN in July, worked at CERN for more than 30 years and led the theory division between 1994 and 1997. (Image credit: CERN-PHOTO-201807-183-1.)

But things weren’t so clear back then. The highly non-trivial jump from QED to QCD meant having the guts to write a theory for entities (quarks) that nobody had ever seen experimentally. No one was ready for such a logical jump, so we tried something else: an S-matrix approach. The S-matrix, which relates the initial and final states of a quantum-mechanical process, allows one to directly calculate the probabilities of scattering processes without solving a quantum field theory such as QED. This is why it looked more promising. It was also looking very conventional but, eventually, led to something even more revolutionary than QCD – the idea that hadrons are actually strings.

Is it true that your “eureka” moment was when you came across the Euler beta function in a textbook?

Not at all! I was taking a bottom-up approach to understand the strong interaction. The basic idea was to impose on the S-matrix a property now known as Dolen–Horn–Schmid (DHS) duality. It relates two apparently distinct processes contributing to an elementary reaction, say a+b → c+d. In one process, a+b fuse to form a metastable state (a resonance) which, after a characteristic lifetime, decays into c+d. In the other process the pair a+c exchanges a virtual particle with the pair b+d. In QED these two processes have to be added because they correspond to two distinct Feynman diagrams, while, according to DHS duality, each one provides, for strong interactions, the whole story. I’d heard about DHS duality from Murray Gell-Mann at the Erice summer school in 1967, where he said that DHS would lead to a “cheap bootstrap” for the strong interaction. Hearing this being said by a great physicist motivated me enormously. I was in the middle of my PhD studies at the Weizmann Institute in Israel. Back there in the fall, a collaboration of four people was formed. It consisted of Marco Ademollo, on leave at Harvard from Florence, and of Hector Rubinstein, Miguel Virasoro and myself at the Weizmann Institute. We worked intensively for a period of eight-to-nine months trying to solve the (apparently not so) cheap bootstrap for a particularly convenient reaction. We got very encouraging results hinting, I was feeling, for the existence of a simple exact solution. That solution turned out to be the Euler beta function.

Veneziano in July 1968 at Lake Annecy

But the 1968 paper was authored by you alone?

Indeed. The preparatory work done by the four of us had a crucial role, but the discovery that the Euler beta function was an exact realisation of DHS duality was just my own. It was around mid-June 1968, just days before I had to take a boat from Haifa to Venice and then continue to CERN where I would spend the month of July. By that time the group of four was already dispersing (Rubinstein on his way to NYU, Virasoro to Madison, Wisconsin via Argentina, Ademollo back to Florence before a second year at Harvard). I kept working on it by myself, first on the boat, then at CERN until the end of July when, encouraged by Sergio Fubini, I decided to send the preprint to the journal Il Nuovo Cimento.

Was the significance of the result already clear?

Well, the formula had many desirable features, but the reaction of the physics community came to me as a shock. As soon as I had submitted the paper I went on vacation for about four weeks in Italy and did not think much about it. At the end of August 1968, I attended the Vienna conference – one of the biennial Rochester-conference series – and found out, to my surprise, that the paper was already widely known and got mentioned in several summary talks. I had sent the preprint as a contribution and was invited to give a parallel-session talk about it. Curiously, I have no recollection of that event, but my wife remembers me telling her about it. There was even a witness, the late David Olive, who wrote that listening to my talk changed his life. It was an instant hit, because the model answered several questions at once, but it was not at all apparent then that it had anything to do with strings, not to mention quantum gravity.

When was the link to “string theory” made?

The first hints that a physical model for hadrons could underlie my mathematical proposal came after the latter had been properly generalised (to processes involving an arbitrary number of colliding particles) and the whole spectrum of hadrons it implied was unraveled (by Fubini and myself and, independently, by Korkut Bardakci and Stanley Mandelstam). It came out, surprisingly, to closely resemble the exponentially growing (with mass) spectrum postulated almost a decade earlier by CERN theorist Rolf Hagedorn and, at least naively, it implied an absolute upper limit on temperature (the so-called Hagedorn temperature).

The spectrum coincides with that of an infinite set of harmonic oscillators and thus resembles the spectrum of a quantised vibrating string with its infinite number of higher harmonics. Holger Nielsen and Lenny Susskind independently suggested a string (or a rubber-band) picture. But, as usual, the devil was in the details. Around the end of the decade Yoichiro Nambu (and independently Goto) gave the first correct definition of a classical relativistic string, but it took until 1973 for Goddard, Goldstone, Rebbi and Thorn to prove that the correct application of quantum mechanics to the Nambu–Goto string reproduced exactly the above-mentioned generalisation of my original work. This also included certain consistency conditions that had already been found, most notably the existence of a massless spin-1 state (by Virasoro) and the need for extra spatial dimensions (from Lovelace’s work). At that point it became clear that the original model had a clear physical interpretation of hadrons being quantised strings. Some details were obviously wrong: one of the most striking features of strong interactions is their short-range nature, while a massless state produces long-range interactions. The model being inconsistent for three spatial dimensions (our world!) was also embarrassing, but people kept hoping.

So string theory was discovered by accident?

Not really. Qualitatively speaking, however, having found that hadrons are strings was no small achievement for those days. It was not precisely the string we now associate with quark confinement in QCD. Indeed the latter is so complicated that only the most powerful computers could shed some light on it many decades later. A posteriori, the fact that by looking at hadronic phenomena we were driven into discovering string theory was neither a coincidence nor an accident.

When was it clear that strings offer a consistent quantum-gravity theory?

This very bold idea came as early as 1974 from a paper by Joel Scherk and John Schwarz. Confronted with the fact that the massless spin-1 string state refused to become massive (there is no Brout–Englert–Higgs mechanism at hand in string theory!) and that even a massless spin-2 string had to be part of the string spectrum, they argued that those states should be identified with the photon and the graviton, i.e. with the carriers of electromagnetic and gravitational interactions, respectively. Other spin-1 particles could be associated with the gluons of QCD or with the W and Z bosons of the weak interaction. String theory would then become a theory of all interactions, at a deeper, more microscopic level. The characteristic scale of the hadronic string (~10^–13 cm) had to be reduced by 20 orders of magnitude (~10^–33 cm, the famous Planck-length) to describe the quarks themselves, the electron, the muon and the neutrinos, in fact every elementary particle, as a string.

In addition, it turned out that a serious shortcoming of the old string (namely its “softness”, meaning that string–string collisions cannot produce events with large deflection angles) was a big plus for the Scherk–Schwarz proposal. While the data were showing that hard hadron collisions were occurring at substantial rates, in agreement with QCD predictions, the softness of string theory could free quantum gravity from its problematic ultraviolet divergences – the main obstacle to formulating a consistent quantum-gravity theory.

Did you then divert your attention to string theory?

Not immediately. I was still interested in understanding the strong interactions and worked on several aspects of perturbative and non-perturbative QCD and their supersymmetric generalisations. Most people stayed away from string theory during the 1974–1984 decade. Remember that the Standard Model had just come to life and there was so much to do in order to extract its predictions and test it. I returned to string theory after the Green–Schwarz revolution in 1984. They had discovered a way to reconcile string theory with another fact of nature: the parity violation of weak interactions. This breakthrough put string theory in the hotspot again and since then the number of string-theory aficionados has been steadily growing, particularly within the younger part of the theory community. Several revolutions have followed since then, associated with the names of Witten, Polchinski, Maldacena and many others. It would take too long to do justice to all these beautiful developments. Personally, and very early on, I got interested in applying the new string theory to primordial cosmology.

Was your 1991 paper the first to link string theory with cosmology?

I think there was at least one already, a model by Brandenberger and Vafa trying to explain why our universe has only three large spatial dimensions, but it was certainly among the very first. In 1991, I (and independently Arkadi Tseytlin) realised that the string-cosmology equations, unlike Einstein’s, admit a symmetry (also called, alas, duality!) that connects a decelerating expansion to an accelerating one. That, I thought, could be a natural way to get an inflationary cosmology, which was already known since the 1980s, in string theory without invoking an ad-hoc “inflaton” particle.

The problem was that the decelerating solution had, superficially, a Big Bang singularity in its past, while the (dual) accelerating solution had a singularity in the future. But this was only the case if one neglected effects related to the finite size of the string. Many hints, including the already mentioned upper limit on temperature, suggested that Big Bang-like singularities are not really there in string theory. If so, the two duality-related solutions could be smoothly connected to provide what I dubbed a “pre-Big Bang scenario” characterised by the lack of a beginning of time. I think that the model (further developed with Maurizio Gasperini and by many others) is still alive, at least as long as a primordial B-mode polarisation is not discovered in the cosmic microwave background, since it is predicted to be insignificant in this cosmology.

Did you study other aspects of the new incarnation of string theory?

A second line of string-related research, which I have followed since 1987, concerns the study of thought experiments to understand what string theory can teach us about quantum gravity in the spirit of what people did in the early days of quantum mechanics. In particular, with Daniele Amati and Marcello Ciafaloni first, and then also with many others, I have studied string collisions at trans-Planckian energies (> 10¹⁹ GeV) that cannot be reached in human-made accelerators but could have existed in the early universe. I am still working on it. One outcome of that study, which became quite popular, is a generalisation of Heisenberg’s uncertainty principle implying a minimal value of Δx of the order of the string size.

50 years on, is the theory any closer to describing reality?

People say that string theory doesn’t make predictions, but that’s simply not true. It predicts the dimensionality of space, which is the only theory so far to do so, and it also predicts, at tree level (the lowest level of approximation for a quantum-relativistic theory), a whole lot of massless scalars that threaten the equivalence principle (the universality of free-fall), which is by now very well tested. If we could trust this tree-level prediction, string theory would be already falsified. But the same would be true of QCD, since at tree level it implies the existence of free quarks. In other words: the new string theory, just like the old one, can be falsified by large-distance experiments provided we can trust the level of approximation at which it is solved. On the other hand, in order to test string theory at short distance, the best way is through cosmology. Around (i.e. at, before, or soon after) the Big Bang, string theory may have left its imprint on the early universe and its subsequent expansion can bring those to macroscopic scales today.

What do you make of the ongoing debate on the scientific viability of the landscape, or “swamp”, of string-theory solutions?

I am not an expert on this subject but I recently heard (at the Strings 2018 conference in Okinawa, Japan) a talk on the subject by Cumrun Vafa claiming that the KKLT solution [which seeks to account for the anomalously small value of the vacuum energy, as proposed in 2003 by Kallosh, Kachru, Linde and Trivedi] is in the swampland, meaning it’s not viable at a fundamental quantum-gravity level. It was followed by a heated discussion and I cannot judge who is right. I can only add that the absence of a metastable de-Sitter vacuum would favour quintessence models of the kind I investigated with Thibault Damour several years ago and that could imply interestingly small (but perhaps detectable) violations of the equivalence principle.

What’s the perception of strings from outside the community?

Some of the popular coverage of string theory in recent years has been rather superficial. When people say string theory can’t be proved, it is unfair. The usual argument is that you need unconceivably high energies. But, as I have already said, the new incarnation of string theory can be falsified just like its predecessor was; it soon became very clear that QCD was a better theory. Perhaps the same will happen to today’s string theory, but I don’t think there are serious alternatives at the moment. Clearly the enthusiasm of young people is still there. The field is atypically young – the average age of attendees of a string-theory conference is much lower than that for, say, a QCD or electroweak physics conference. What is motivating young theorists? Perhaps the mathematical beauty of string theory, or perhaps the possibility of carrying out many different calculations, publishing them and getting lots of citations.

What advice do you offer young theorists entering the field?

I myself regret that most young string theorists do not address the outstanding physics questions with quantum gravity, such as what’s the fate of the initial singularity of classical cosmology in string theory. These are very hard problems and young people these days cannot afford to spend a couple of years on one such problem without getting out a few papers. When I was young I didn’t care about fashions, I just followed my nose and took risks that eventually paid off. Today it is much harder to do so.

How has theoretical particle physics changed since 1968?

In 1968 we had a lot of data to explain and no good theory for the weak and strong interactions. There was a lot to do and within a few years the Standard Model was built. Today we still have essentially the same Standard Model and we are still waiting for some crisis to come out of the beautiful experiments at CERN and elsewhere. Steven Weinberg used to say that physics thrives on crises. The crises today are more in the domain of cosmology (dark matter, dark energy), the quantum mechanics of black holes and really unifying our understanding of physics at all scales, from the Planck length to our cosmological horizon, two scales that are 60 orders of magnitude apart. Understanding such a hierarchy (together with the much smaller one of the Standard Model) represents, in my opinion, the biggest theoretical challenge for 21st century physics.

What are String Variables? | Kodable Help Center

NOTE: Learners are first introduced to string variables in Asteroidia. To learn more about strings and other concepts, check out the full learning guide for Asteroidia –> click HERE. 

Variables store information in a program. You can think of variables like a box or a container with a name on them, related to the things inside. These items inside are called values, which can be stored as text or numbers. When you use a variable in a program you’re able to control the output of the program, or what a user sees.

There are many different types of values that can be stored in a variable. In Kodable, we focus on three: Strings, Integers, and Arrays.

A string is a type of value that can be stored in a variable. A string is made up of characters, and can include letters, words, phrases, or symbols.

Definition: Strings hold groups of characters, like a word or a phrase.

In Real Life: An easy way to think about strings in real life is to think about the way your brain stores people’s names. Think of a person as a variable here: a name is just like a string: it as a value that your brain uses to identify a person. Variables have values that can change, or vary, just like a person’s last name can change when they get married, or a friend starts calling then by a new nickname.

In Programming: In programming, strings allow programmers to easily store, find, and change information in a program.

In Kodable, learners practice storing strings, which are represented by colors. When learners put a color in the command bin, they are assigning a value to the variable. Learners will match the variable with an asteroid type to clear the asteroid field.

When like asteroids touch in the asteroid field, they will clear on their own. Learners need to think critically and use as few variables as possible to clear the asteroid field.

In this level, we can see how learners will assign values to variables by using the colored fuzzballs on the left. Like-variables will clear on their own.

Let’s think about how strings work in programming- we can think about video games and how a game developer controls what the player sees. A character’s name, hair color and eye color are stored as strings in a video game, making it easy for programmers to know or change what variables represent specific information in the code. A programmer working on the game could type in the variable for the character’s eye color and edit the value from “blue” to “brown”, instantly changing the character’s eye color in the game.

Why We Use Strings: String variables allow programmers to easily find information in their code and reuse values in their programs. Variables can change- think vary- and strings make it easy for programmers to read and change values assigned to different variables throughout their programs.

Python Strings (With Examples)

What is String in Python?

A string is a sequence of characters.

A character is simply a symbol. For example, the English language has 26 characters.

Computers do not deal with characters, they deal with numbers (binary). Even though you may see characters on your screen, internally it is stored and manipulated as a combination of 0s and 1s.

This conversion of character to a number is called encoding, and the reverse process is decoding. ASCII and Unicode are some of the popular encodings used.

In Python, a string is a sequence of Unicode characters. Unicode was introduced to include every character in all languages and bring uniformity in encoding. You can learn about Unicode from Python Unicode.

How to create a string in Python?

Strings can be created by enclosing characters inside a single quote or double-quotes. Even triple quotes can be used in Python but generally used to represent multiline strings and docstrings.

# defining strings in Python
# all of the following are equivalent
my_string = 'Hello'
print(my_string)

my_string = "Hello"
print(my_string)

my_string = '''Hello'''
print(my_string)

# triple quotes string can extend multiple lines
my_string = """Hello, welcome to
           the world of Python"""
print(my_string)

When you run the program, the output will be:

Hello
Hello
Hello
Hello, welcome to
           the world of Python

How to access characters in a string?

We can access individual characters using indexing and a range of characters using slicing. Index starts from 0. Trying to access a character out of index range will raise an IndexError. The index must be an integer. We can’t use floats or other types, this will result into TypeError.

Python allows negative indexing for its sequences.

The index of -1 refers to the last item, -2 to the second last item and so on. We can access a range of items in a string by using the slicing operator :(colon).

#Accessing string characters in Python
str = 'programiz'
print('str = ', str)

#first character
print('str[0] = ', str[0])

#last character
print('str[-1] = ', str[-1])

#slicing 2nd to 5th character
print('str[1:5] = ', str[1:5])

#slicing 6th to 2nd last character
print('str[5:-2] = ', str[5:-2])

When we run the above program, we get the following output:

str =  programiz
str[0] =  p
str[-1] =  z
str[1:5] =  rogr
str[5:-2] =  am

If we try to access an index out of the range or use numbers other than an integer, we will get errors.

# index must be in range
>>> my_string[15]  
...
IndexError: string index out of range

# index must be an integer
>>> my_string[1.5] 
...
TypeError: string indices must be integers

Slicing can be best visualized by considering the index to be between the elements as shown below.

If we want to access a range, we need the index that will slice the portion from the string.

String Slicing in Python

How to change or delete a string?

Strings are immutable. This means that elements of a string cannot be changed once they have been assigned. We can simply reassign different strings to the same name.

>>> my_string = 'programiz'
>>> my_string[5] = 'a'
...
TypeError: 'str' object does not support item assignment
>>> my_string = 'Python'
>>> my_string
'Python'

We cannot delete or remove characters from a string. But deleting the string entirely is possible using the del keyword.

>>> del my_string[1]
...
TypeError: 'str' object doesn't support item deletion
>>> del my_string
>>> my_string
...
NameError: name 'my_string' is not defined

Python String Operations

There are many operations that can be performed with strings which makes it one of the most used data types in Python.

To learn more about the data types available in Python visit: Python Data Types

Concatenation of Two or More Strings

Joining of two or more strings into a single one is called concatenation.

The + operator does this in Python. Simply writing two string literals together also concatenates them.

The * operator can be used to repeat the string for a given number of times.

# Python String Operations
str1 = 'Hello'
str2 ='World!'

# using +
print('str1 + str2 = ', str1 + str2)

# using *
print('str1 * 3 =', str1 * 3)

When we run the above program, we get the following output:

str1 + str2 =  HelloWorld!
str1 * 3 = HelloHelloHello

Writing two string literals together also concatenates them like + operator.

If we want to concatenate strings in different lines, we can use parentheses.

>>> # two string literals together
>>> 'Hello ''World!'
'Hello World!'

>>> # using parentheses
>>> s = ('Hello '
...      'World')
>>> s
'Hello World'

Iterating Through a string

We can iterate through a string using a for loop. Here is an example to count the number of ‘l’s in a string.

# Iterating through a string
count = 0
for letter in 'Hello World':
    if(letter == 'l'):
        count += 1
print(count,'letters found')

When we run the above program, we get the following output:

3 letters found

String Membership Test

We can test if a substring exists within a string or not, using the keyword in.

>>> 'a' in 'program'
True
>>> 'at' not in 'battle'
False

Built-in functions to Work with Python

Various built-in functions that work with sequence work with strings as well.

Some of the commonly used ones are enumerate() and len(). The enumerate() function returns an enumerate object. It contains the index and value of all the items in the string as pairs. This can be useful for iteration.

Similarly, len() returns the length (number of characters) of the string.

str = 'cold'

# enumerate()
list_enumerate = list(enumerate(str))
print('list(enumerate(str) = ', list_enumerate)

#character count
print('len(str) = ', len(str))

When we run the above program, we get the following output:

list(enumerate(str) =  [(0, 'c'), (1, 'o'), (2, 'l'), (3, 'd')]
len(str) =  4

Python String Formatting

Escape Sequence

If we want to print a text like He said, “What’s there?”, we can neither use single quotes nor double quotes. This will result in a SyntaxError as the text itself contains both single and double quotes.

>>> print("He said, "What's there?"")
...
SyntaxError: invalid syntax
>>> print('He said, "What's there?"')
...
SyntaxError: invalid syntax

One way to get around this problem is to use triple quotes. Alternatively, we can use escape sequences.

An escape sequence starts with a backslash and is interpreted differently. If we use a single quote to represent a string, all the single quotes inside the string must be escaped. Similar is the case with double quotes. Here is how it can be done to represent the above text.

# using triple quotes
print('''He said, "What's there?"''')

# escaping single quotes
print('He said, "What\'s there?"')

# escaping double quotes
print("He said, \"What's there?\"")

When we run the above program, we get the following output:

He said, "What's there?"
He said, "What's there?"
He said, "What's there?"

Here is a list of all the escape sequences supported by Python.

Here are some examples

>>> print("C:\\Python32\\Lib")
C:\Python32\Lib

>>> print("This is printed\nin two lines")
This is printed
in two lines

>>> print("This is \x48\x45\x58 representation")
This is HEX representation

Raw String to ignore escape sequence

Sometimes we may wish to ignore the escape sequences inside a string. To do this we can place r or R in front of the string. This will imply that it is a raw string and any escape sequence inside it will be ignored.

>>> print("This is \x61 \ngood example")
This is a
good example
>>> print(r"This is \x61 \ngood example")
This is \x61 \ngood example

The format() Method for Formatting Strings

The format() method that is available with the string object is very versatile and powerful in formatting strings. Format strings contain curly braces {} as placeholders or replacement fields which get replaced.

We can use positional arguments or keyword arguments to specify the order.

# Python string format() method

# default(implicit) order
default_order = "{}, {} and {}".format('John','Bill','Sean')
print('\n--- Default Order ---')
print(default_order)

# order using positional argument
positional_order = "{1}, {0} and {2}".10}|{:>10}|".format('butter','bread','ham')
'|butter    |  bread   |       ham|'

Old style formatting

We can even format strings like the old sprintf() style used in C programming language. We use the % operator to accomplish this.

>>> x = 12.3456789
>>> print('The value of x is %3.2f' %x)
The value of x is 12.35
>>> print('The value of x is %3.4f' %x)
The value of x is 12.3457

Common Python String Methods

There are numerous methods available with the string object. The format() method that we mentioned above is one of them. Some of the commonly used methods are lower(), upper(), join(), split(), find(), replace() etc. Here is a complete list of all the built-in methods to work with strings in Python.

>>> "PrOgRaMiZ".lower()
'programiz'
>>> "PrOgRaMiZ".upper()
'PROGRAMIZ'
>>> "This will split all words into a list".split()
['This', 'will', 'split', 'all', 'words', 'into', 'a', 'list']
>>> ' '.join(['This', 'will', 'join', 'all', 'words', 'into', 'a', 'string'])
'This will join all words into a string'
>>> 'Happy New Year'.find('ew')
7
>>> 'Happy New Year'.replace('Happy','Brilliant')
'Brilliant New Year'

String Interpolation in JavaScript

String interpolation is replacing placeholders with values in a string literal.

The string interpolation in JavaScript is performed by template literals (strings wrapped in backticks `) and ${expression} as a placeholder. For example:

const number = 42;
const message = `The number is ${number}`;

message; 

Let’s see in more detail, with examples and best practices, how to use template strings to perform string interpolation in JavaScript.

1. The string literals

In JavaScript, there are 3 ways to create string literals.

First, which I prefer for plain strings, is to wrap the string into a pair of single quotes ':

const message = 'Hello, World!';

The second, which I use rarely, is to wrap the string into a pair of double quotes ":

const message = "Hello, World";

The third, which permits string interpolation, is to wrap the string into a pair of backticks `:

const message = `Hello, World!`;

The string literal wrapped in backticks ` is also named template string. This is the literal that supports the string interpolation.

2. The placeholders

The template string supports placeholders. The expression inside the placeholder is evaluated during runtime, and the result is inserted into the string.

The placeholder has a special format: ${expressionToEvaluate}. The expression inside the placeholder can be of any kind:

• variables: ${myVar}
• operators: ${n1 + n2}, ${cond ? 'val 1' : 'val 2'}
• even function calls ${myFunc('argument')}

Here’s an example:

const greeting = 'Hello';
const who = 'World';

const message = `${greeting}, ${who}!`;message; 

`${greeting}, ${who}!` is a template string having placeholders ${greeting} and ${who}.

On script execution, the first placeholder ${greeting} is replaced with the value of greeting variable, and the same for ${who}. The string interpolation result is 'Hello, World!'.

You can put any expression inside the placeholder: either an operator, a function call, or even more complex expressions.

const n1 = 2;
const n2 = 3;

const message1 = `The sum is ${n1 + n2}`;message1; 

function sum(num1, num2) {
  return num1 + num2;
}
const message2 = `The sum is ${sum(n1, n2)}`;message2; 

${n1 + n2} is a placeholder consisting of the addition operator and 2 operands.

While the placeholder ${sum(n1, n2)} contains a function invocation.

2.1 Implicit to string conversion

The placeholder expression result is implicitly converted to a string.

For example, a number in a placeholder is transformed into a string:

const n = 3.5;
const message = `The number is ${n}`;

message; 

The expression n of the placeholder ${n} is evaluated to number 3.5. The number 3.5 is then transformed into a string '3.5', and inserted into the interpolation result: 'The number is 3.5'.

If the placeholder contains an object, following the conversion to string rule, the object is converted to a string too. The toString() method of the object is called to get the string representation of the object.

For example, let’s insert an array into a template string:

const numbers = [1, 2, 3];
const message = `The numbers are ${numbers}`;

message; 

The placeholder ${numbers} contains an array of numbers.

toString() array method executes array.join(',') when the array is converted to string. Thus the string interpolation result is 'The numbers are 1,2,3'.

3. Escaping placeholders

Because the placeholder format ${expression} has a special meaning in the template literals, you cannot use the sequence of characters "${someCharacters}" without escaping.

For example, let’s try to create a string literal containing the sequence of characters ${abc}:

const message = `Some weird characters: ${abc}`;

Inserting ${abc} directly throws an error because JavaScript interprets ${abc} as a placeholder.

A backslash \ before the placeholder-like sequence of characters \${abc} solves the problem:

const message = `Some weird characters: \${abc}`;
message; 

In the template string `Some weird characters: \${abc}` JavaScript interprets \${abc} as a sequence of characters, rather than a placeholder.

Alongside with ${abc}, the sequence of characters like ${abc and ${ also have to be escaped with a backslash \:

const message = `Some weird characters: \${abc} \${abc \${`;

message; 

4. Best practices

4.1 Refactor string concatentation

The string interpolation should be used instead of string concatenation to construct lengthy strings.

If for some reason you’re still concatenating string literals and expressions using + operator:

const n1 = 2;
const n2 = 3;
const message = 'The sum of ' + n1 + ' and ' + n2 + ' is ' + (n1 + n2);
message; 

Then it’s the time to switch to string interpolation using template strings:

const n1 = 2;
const n2 = 3;
const message = `The sum of ${n1} and ${n2} is ${n1 + n2}`;
message; 

The template string usage requires less code and is easier to read.

4.2 Helper variables

When the template string contains many complex expressions, it might decrease the readability of the literal.

Here’s a template string having placeholders with complex expressions:

const n1 = 2;
const n2 = 3;

const message = 
  `Sum: ${n1 + n2}, difference: ${n1 - n2}, pow: ${Math.pow(n1, n2)}`;

message; 

The more complex the placeholders are, the more tempting is to add helper variables to store intermediate values.

const n1 = 2;
const n2 = 3;

const sum = n1 + n2;const diff = n1 - n2;const pow = Math.pow(n1, n2);
const message = `Sum: ${sum}, difference: ${diff}, pow: ${pow}`;

message; 

With the introduction of helper variables sum, diff, and pow, the template string becomes lighter. Additionally, the code self-documents when the intermediate variables are used.

4.3 Single quotes in placeholders

I recommended using single quotes ' rather than backticks ` in the expressions inside the placeholder.

Let’s use the ternary operator. When the placeholder uses backticks ` it’s quite difficult to grasp the template string because there are too many backticks in the template string:

function getLoadingMessage(isLoading) {
  return `Data is ${isLoading ? `loading...` : `done!`}`;}

But using single quotes inside the placeholder just looks better:

function getLoadingMessage(isLoading) {
  return `Data is ${isLoading ? 'loading...' : 'done!'}`;}

4.4 Alternative solutions

The string interpolation is helpful in many situations. But when the template string becomes large, with complex placeholder expressions, you might look for other solutions.

The following component builds the CSS class based on 2 variables:

function LoadingMessage({ isLoading, isModal }) {
  const className = 
   `${isLoading ? 'loading' : ''} ${isModal ? 'modal' : ''}`;
  return (
    <div className={className}>
      {isLoading ? 'Loading...' : 'Done!'}
    </div>
  );
}

The template literal that determines the class name has 2 ternary operators and a mix of string literals. You may find it difficult to understand.

A tool like classnames might be a better choice than template string. The tool constructs the class name
in a more declarative way.

Let’s refactor the component to use classnames:

import classNames from 'classnames';

function LoadingMessage({ isLoading, isModal }) {
  const className = classNames({    loading: isLoading,    modal: isModal  });
  return (
    <div className={className}>
      {isLoading ? 'Loading...' : 'Done!'}
    </div>
  );
}

This version of the component, which uses the classnames tool, is easier to understand than the template string version.

Adding more CSS classes (for example to handle isErrorLoading) would not decrease the readability of the version that uses classnames utility (contrary to using a template literal).

5. String interpolation in TypeScript

The string interpolation in TypeScript works the same way as in JavaScript:

const count: number = 10;
const message: string = `You have ${count} products`;

message; 

6. String interpolation in React

The string interpolation in React consists of 2 cases:

• Attribute interpolation: attribute={`My string ${placeholder}`}
• Element’s text interpolation: <span>My string {placeholder}</span>

Here’s an example that shows both cases:

import React from 'react';

export function BuyProductsButton({ count, buy }) {
  return (
    <button
      title={`Buy ${count} products`}      onClick={buy}
    >
      Buy {count} products    </button>
  );
}

<BuyProductsButton count={10} buy={() => {}} /> would render the output:

<button title="Buy 10 products">
  Buy 10 products
</button>

During the interpolation of both attribute and text strings, placeholders ${count} and correspondingly {count} are replaced with 10.

7. Conclusion

The string interpolation is a great feature because it helps to insert values into string literals in a concise and readable manner. And avoid the clumsy string concatenation approach.

In JavaScript, the template string implements the string interpolation.

A template string is defined by wrapping a sequence of characters into a pair of backticks `I'm template string`. The template string placeholders have the format ${expression}, for example `The number is ${number}`.

Don’t overcomplicate the string literal. If the template string uses complex expressions, try to introduce intermediate variables to store the expressions before putting them into placeholders.

As soon as you need a value inserted into a string literal, the template string is the way to go.

90,000 EXPRESS in 1C 8.3 request: as a number, as string

The “EXPRESS” operator in the 1C 8.3 query language is used in two cases:

• When it is necessary to convert a string or numeric data type to the desired type (format)
• To select one type, in the selection fields of a composite data type.

Let’s look at the examples of the operation of such an operator.

EXPRESS AS String

To work with a string data type, such an operator can be useful when you need to hard-code the dimension of a string.

Syntax:

EXPRESS ( AS String ())

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Example:

SELECT

EXPRESS (Nomenclature. Item AS String (1)) AS Item Length_1

FROM

Reference.Nomenclature AS Nomenclature

In this example, we select all the names from the Nomenclature reference book, then using the EXPRESS construction together with the String operator, we limit the size of the selection field line to one character.

EXPRESS AS Number

Using the EXPRESS operator, it is possible to control the length of the integer and fractional parts of the number in the query selection fields that have a numeric data type. In cases where, as a result of such control, the number of digits in the number will be reduced, rounding will occur according to mathematical rules.

Syntax:

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EXPRESS ( AS Number (. ))

Example # 1:

SELECT

3.55 AS Our Number,

EXPRESS (3.55 AS Number (15,1)) AS Rounding Result

Result:

Example # 2:

SELECT

10/3 AS Result,

EXPRESS (10/3 AS Number (15.2)) AS Rounding result

Result:

Looking at the results of the examples, it is clear that the EXPRESS operator rounds numbers to the nearest integer.

EXPRESS for composite data type and query optimization

Using the “EXPRESS” operator, for fields with a complex data type, it is possible to restrict the entry of values ​​that do not correspond to a certain data type. Moreover, such restrictions can be made even at the stage of data sampling. Such actions lead to implicit query optimization. Let’s take a closer look at an example.

There is a query that selects all buyers from the “Selling Goods” documents existing in the document base.For documents of this type, the requisite “Buyer” has a composite data type:

• .

Request:

SELECT

Sale

Sale of Goods. Buyer AS Buyer Reference

FROM

Document.Sale of Goods AS Selling Goods

Result:

It should be understood that the data in the “CustomerLink” field is formed by an implicit left join with the “Contractors” tables.Link “from the directory” Contracts “and” Employees.Link “from the directory” Employees “. Such connections in 1C requests occur when we access the subordinate field through a dot (dereference the field). In our case, we refer to the field “Buyer”.

Visual representation of the operation of such a request:

If the task was to select only those documents in which the employee was the buyer. The most optimal solution from the point of view of the query execution speed would be to completely prohibit access to the “Contractors” directory, since the data from this directory is superfluous for us.The EXPRESS operator can easily cope with such a task, and the query might look like this:

Request:

SELECT

Sale

EXPRESS (Selling Goods.Buyer AS Directory.Employees) AS BUYER’S REFERENCE

FROM

Document.Sale of Goods AS Selling Goods

Result:

However, as we can see from the query result, the selection fields that do not meet the conditions of our selection received NULL values.Therefore, when implementing selections using the “EXPRESS” construction, in order to avoid further errors, it is correct to impose an additional condition, for example, using the “Where” operator. Then the request might look like this:

Request:

SELECT

Sale

EXPRESS (Selling Goods.Buyer AS Directory.Employees) AS BUYER’S REFERENCE

FROM

Document.Sale of Goods AS Selling Goods

Where

Sale of Goods.Buyer REFERENCE Reference. Employees

Result:

Possible errors

Data type conversion is not possible with the EXPRESS operator. For example, string to number:

SELECT

EXPRESS (“123” AS Number (15,2)) AS Number

When executing such a request, we will inevitably receive the following error:

Strings in C ++ (class string)

Strings in C ++ (class string)

In C ++, for convenient work with strings, there is a class string, for which you need to connect the header file string.

Strings can be declared and assigned values ​​at the same time:

String S1 will be empty, string S2 will be 5 characters long.

Individual characters in a string can be referenced by index as elements of an array or C strings. For example S [0] is the first character of the string.

In order to find out the length of a string, you can use the size () method of the string. For example, the last character of string S is S [S.size () – 1].

C ++ strings can

String constructors

Strings can be created using the following constructors:
string () – The default constructor (no parameters) creates an empty string.
string (string & S) – copy of string S
string ( size_t n, char c) – repetition of character c specified number n times.
string (size_t c) – a single character string c .
string (string & S, size_t start, size_t len) – a string containing no more than len characters of this string S , starting from character number start .

Constructors can be called explicitly, for example, like this:

This example explicitly calls the constructor string to create a 10 character string 'z' .

The constructor is implicitly called when a string is declared with additional parameters. For example, like this:

Read more about string constructors here.

I / O strings

The string is output in the same way as numeric values:

To read the string, you can use the “>>” operation for the cin object:

In this case, a string of non-whitespace characters is read, omitting spaces and line ends.This is useful for breaking text into words, or for reading data to the end of the file using while (cin >> S).

You can read lines until the end-of-line character appears using the getline function. The end-of-line character itself is read from the input stream, but is not added to the string:

Arithmetic Operators

The following arithmetic operations can be performed with strings:
= – value assignment.
+ = – Adds another string or character to the end of the string.
+ – concatenate two strings, concatenate a string and a character.
== , ! = is a character-by-character comparison.
<, > , <= , > = - lexicographic comparison.

That is, you can copy the contents of one string to another using the operation S1 = S2, compare two strings for equality using S1 == S2, compare the strings in lexicographic order using S1

Read more about string operators here.

String Methods

Strings have different methods, many of which can be used in several different ways (with different sets of parameters).

Let's consider these methods in more detail.

size

The size () method returns the length of the string. The return value is an unsigned type (as in all cases, when the function returns a value equal to the length of the string or the index of the element - these values ​​are unsigned).Therefore, you need to carefully perform the operation of subtracting from the value returned by size (). For example, it would be wrong to write a loop that iterates over all characters of a string except the last one in the form for (int i = 0; i

In addition, strings have a length () method that also returns the length of a string.

More details about the size method.

resize

S.resize (n) - Changes the length of the string, the new length of the string becomes n. In this case, the line can both decrease and increase.If called in the form S.resize (n, c), where c is a character, then when the length of the string increases, the added characters will be equal to c.

Learn more about the resize method.

clear

S.clear () - clears a line, the line becomes empty.

Learn more about the clear method.

empty

S.empty () - returns true if the string is empty, false if it is not empty.

Learn more about the empty method.

push_back

S.push_back (c) - adds the character c to the end of the string, is called with one parameter of the char type.

Learn more about the push_back method.

append

Appends several characters to the end of a string, another string, or a portion of another string. Has many ways to call.

S.append (n, c) - appends n identical characters equal to s to the end of the string. n is of integer type, c is char.

S.append (T) - appends the contents of string T to the end of string S. T can be a string object or a C string.

S.append (T, pos, count) - appends the characters of the string T to the end of the string S starting from the character with the index pos with the number of count.

Learn more about the append method.

erase

S. erase (pos) - deletes from string S from the character with index pos to the end of the string.

S. erase (pos, count) - deletes from the string S from the character with the index pos by count or to the end of the string if pos + count> S.size ().

Learn more about the erase method.

insert

Inserts several characters in the middle of a line, another line, or a portion of another line. The calling methods are similar to the append method, except that the first parameter is the value i, the position at which characters are inserted.The first inserted character will be at index i, and all characters that were previously at index i or more are shifted to the right.

S.insert (i, n, c) - insert n identical characters equal to c. n is of integer type, c is char.

S.insert (i, T) - insert the contents of the string T. T can be an object of the string class or a C-string.

S.insert (i, T, pos, count) - insert characters of string T starting from the character with index pos with count.

Learn more about the insert method.

substr

S.substr (pos) - Returns a substring of the given string starting at the character with index pos to the end of the string.

S.substr (pos, count) - returns a substring of the given string starting from the character with index pos with count or to the end of the string if pos + count> S.size ().

Learn more about the substr method.

replace

Replaces a portion of a string with several equal characters, another string, or a portion of another string. The calling methods are similar to the append method, except that the first two parameters are two numbers: pos and count.Count characters are removed from this string, starting with pos, and new characters are inserted in their place.

S.replace (pos, count, n, c) - insert n identical symbols equal to s. n is of integer type, c is char.

S.replace (pos, count, T) - insert the contents of the string T. T can be an object of the string class or a C-string.

S.replace (pos, count, T, pos2, count2) - insert the characters of the string T starting from the character with the pos index with the number of count.

Learn more about the replace method.

find

Searches the given string for the first occurrence of another string str. The number of the first character is returned, starting from which the next is the substring equal to the string str. If this string is not found, then the constant string :: npos is returned (which is -1, but it is unsigned, that is, in fact, it is a large unsigned positive number).

If pos is specified, the search starts at pos, that is, the return value will be no less than pos.If the pos value is not specified, then it is considered to be 0 - the search is performed from the beginning of the string.

S.find (str, pos = 0) - search for the first entry of str starting from pos. If pos is not specified, then starting from the beginning of string S.

S.find (str, pos, n) - search in this string for a substring equal to the first n characters of string str. Pos must be specified.

Learn more about the find method.

rfind

Searches for the last occurrence of a substring ("right" search).The calling methods are the same as calling the find method.

Learn more about the rfind method.

find_first_of

Searches the given string for the first occurrence of any character in the given string str. The number of this character or the value of string :: npos is returned.

If pos is specified, the search starts at pos, that is, the return value will be no less than pos. If the pos value is not specified, then it is considered to be 0 - the search is performed from the beginning of the string.

S.find_first_of (str, pos = 0) - search for the first entry of any character of string str starting at position pos. If pos is not specified, then starting from the beginning of line S.

More details about the find_first_of method.

find_last_of

Searches the given string for the last occurrence of any character in the given string str. Calling methods and return value are similar to find_first_of method.

Learn more about the find_last_of method.

find_first_not_of

Searches the given string for the first occurrence of a character other than str.Calling methods and return value are similar to find_first_of method.

Learn more about the find_first_not_of method.

find_last_not_of

Searches the given string for the last occurrence of a character other than str. Calling methods and return value are similar to find_first_of method.

Learn more about the find_last_not_of method.

c_str

Returns a pointer to the memory area that stores characters in a string, returns a char * value.The return value can be thought of as a C string and used in functions that must receive a C string as input.

More details about the c_str method.

How to freeze a row and a column in Excel when scrolling

When working with a large amount of data in Excel, we often encounter a situation when scrolling through long lists we get lost and forget which column with data belongs to which criterion. In order to avoid such situations, Excel has the ability to freeze rows and columns.

To do this, we need:

• Go to the “View” tab in Excel => Subsection “Window” => Section “Freeze Areas”:

Three options are available in this menu:

• Freeze Areas : With this function Excel freezes both rows and columns at the same time;
• Freeze Top Row : By default, Freezes the top row of an Excel worksheet;
• Freeze First Column : By default, Freezes the first column on the Excel sheet to the left.

Video tutorial: How to freeze a row and a column in Excel when scrolling

How to freeze a row when scrolling in Excel

table headers, as shown below:

In situations like this, it is best to use the pinning of the top row of an Excel sheet. Docking will allow you to see the table headings as you scroll.

In order to fix the top row, we need:

• Go to the “View” tab in Excel => Subsection “Window” => section “Freeze areas”:

• In the drop-down menu, select “Freeze Top Row ”:

After that, a gray thin line will appear, indicating the presence of a pinned top row:

Now, you can scroll through the table data, while keeping the table headers:

How to pin more than one row in Excel

If in our table headers occupy more than one line, then we need to freeze two or more lines.To do this:

• Select the cell on the left, located under the lines with titles:

• Go to the "View" tab in Excel => "Window" subsection => "Freeze areas" section:

• In the drop-down menu, select “Freeze Areas”:

After that Excel will freeze all the lines on top of the cell you selected. Now, when scrolling, two rows with titles will become fixed:

How to unpin a row in Excel

To unpin rows, follow these steps:

• Go to the "View" tab in Excel => Subsection "Window" = > section “Freeze areas”:

• In the drop-down lists, select “Unpin areas”:

How to freeze a column when scrolling in Excel

If the table headers are located in the leftmost column, then when scrolling horizontally headers will disappear.Anchoring the first column will help us to avoid this. To do this, we need:

• Go to the “View” tab in Excel => “Window” subsection => “Freeze areas” section:
• In the drop-down menu, select “Freeze first column”:

After this will freeze the leftmost column. A thin gray line indicates the presence of a pinned column:

Now, we can scroll the table horizontally without losing headers:

In addition:

• If you pinned a column, press Ctrl + Z cannot be unpinned from an area.You can remove the docking only through the “Freeze Areas” menu.
• If you insert a column in front of the one that has been pinned, the new column will also be the pinned column.

How to fix more than one column in Excel

If your table contains headers in more than one column and you want to fix them, then do the following:

• Select the topmost cell in the column immediately after the columns that you want to anchor:

• Go to the “View” tab in Excel => “Window” subsection => “Freeze Areas” section:

• In the drop-down menu, select “Freeze Areas ”:

After that, Excel will freeze all columns to the left of the cell you selected.Now, when scrolling, both columns with titles have become fixed:

How to unpin a column in Excel

To unpin columns, follow these steps:

• Go to the "View" tab in Excel => "Window" subsection => section “Freeze areas”:

• In the drop-down list select “Unpin areas”:

How to freeze a row and a column while scrolling in Excel at the same time

Often, for convenience in working with large arrays data, you must freeze both the columns and rows of the table at the same time.

In order to simultaneously freeze rows and columns in Excel, we will do the following steps:

• Select the cell located at the intersection of the columns and rows that we want to freeze. It is important that the cell is not inside the range, but immediately after the required rows and columns. In the example below, we have selected a cell in order to fix the first two columns and the top line:

• Go to the “View” tab in Excel => “Window” subsection => “Freeze areas” section:

• In the drop-down menu, select “Freeze areas”:

Now, when scrolling the data horizontally and vertically, the columns and row of our table are fixed:

To unpin rows and columns, do the following steps:

• Go to the “View” tab in Excel => “Window” subsection => “Freeze Areas” section:

• In the drop-down list, select “Unpin Areas”:

More useful tricks Learn how to work with lists of data and functions in Excel in Hands-On Course “Beginner to Excel Wizard” .Hurry up to register at the link !

string is ... What is string?

New line in the payment: how the fee for garbage collection is charged

The fact is that garbage collection has ceased to be a housing service, for which the management companies (MC) were responsible, and has passed into the category of utilities, which is implemented by regoperators.And the fee has increased, because their tariff now includes:

• collection;
• transportation;
• sorting;
• neutralization;
• waste disposal;
• maintenance of contracts with waste owners.

In this case, monthly calculations are made according to one of two possible formulas:

• housing area * regoperator's rate * accumulation rate per sq. m by region / 12 - if your region decided to keep the calculation scheme by square meters;
• number of residents * rate of the regoperator * rate of accumulation per person by region / 12 - with a new settlement scheme, taking into account the number of people registered in the apartment / house.

For example, owners of an apartment of 50 sq. m in Dolgoprudny - the Moscow region continues to calculate the payment taking into account square meters - you will have to pay:

• 50 (sq. m) * 866.1 (regoperator's tariff) * 0.114 (the rate of accumulation in the Moscow region) / 12 = 411.4 rubles.

But for the residents of Yaroslavl, the size of the living space does not matter - here the amount of payment is calculated based on the number of registered residents:

• 2 (number of residents) * 422.06 (rate of the regoperator until June 30, 2019) * 2.138 (accumulation rate per person in the Yaroslavl region) / 12 = 150.39 rubles.

What kind of scheme operates directly in your subject, you can check with the regional operator or the management company.

Head of the Association of Chairmen of Councils of Apartment Buildings in the Moscow Region Yulia Belekhova gave an example of what constitutes a tariff for one of the regional operators: 53% is collection and transportation, 41% is processing, neutralization, burial, and about 6% is to service contracts. At the same time, within these points, 0.6% are taken into account, which are included in the profit of the regional operator.

Three qubits of the Zuchongzhi calculator have complicated the task of generating a random string by hundreds of times

Yulin Wu et al. / arXiv.org, 2021

Zuchongzhi quantum computer based on superconductors,
developed by Chinese physicists, turned out to be 2-3 orders of magnitude faster than the company's Sycamore
Google.They used a 56-qubit processor and experimentally demonstrated its superiority over the classical one. A preprint of the work is published at arXiv.org .

Two years ago, Google announced that it had achieved quantum supremacy on a computing machine of 53 superconducting qubits, which they called Sycamore. They showed that a quantum calculator copes faster than a classical one with the task of generating a random string - after applying a known random sequence of operations on the initial state of the calculator, the probability distribution obtained at the output is measured and compared with the theoretical one.IBM criticized the results of the experiment, claiming that a classic supercomputer would take thousands of times less time if a different classical algorithm was used. Later, a team of scientists from Google turned to applied problems and calculated on Sycamore the energies of the ground state of hydrogen chains and were able to describe a chemical reaction.

A team of physicists led by Jian-Wei Pan from the University of Science and Technology of China showed how much more powerful a quantum computer becomes when the number of qubits increases from 53 to 56.The authors used 56 qubits of a 66-qubit quantum computer and measured the accuracy of using one-qubit, two-qubit
operations and reading of qubits. In order to estimate the power of the calculator,
the authors used it to solve the problem of generating a random string.

The quantum processor has a two-dimensional lattice architecture
of 66 superconducting transmon qubits, which you can learn more about in our course on quantum technology. Each qubit (except for the extreme ones) is associated with
four neighboring ones with the help of a special qubit that regulates the degree of interaction.In fact, this is the same transmon, but operating at a different frequency - this allows
separate control of different types of qubits.

After physicists were experimentally convinced that
errors received when performing operations on one or two qubits are not
exceed one percent, and the read error is 4.5 percent, they
moved on to generating random quantum sequences. Random sequence
or a string can be generated by a random quantum scheme: to a two-dimensional lattice
qubits are used sequentially "layers" of one-qubit and two-qubit
operations.In one cycle, each qubit is randomly subjected to one of three transformations
and one two-qubit, which changes from cycle to cycle in a certain sequence,
and after all the cycles and immediately before the measurement, we have all the qubits again
perform random one-qubit operations.

. Scheme of cyclic transformation of the circuit: one-qubit transformations are marked in light blue, and different two-qubit transformations are marked in yellow, green, blue and red.The same transformations are indicated on the two-dimensional lattice

Yulin Wu et al. / arXiv.org, 2021

Even a small number of loops can lead to confusing
condition with high probability. Nevertheless, the authors used a scheme of 20
cycles on 56 qubits and compared the results with calculations of the classical
computer. Simulating the problem becomes overwhelming as the number of cycles increases.
for a classical computer, therefore, to evaluate its physics performance
use simplified circuit models - they either split the circuit into two separate
parts and transform them in parallel, or remove several two-qubit sublayers
at the beginning.Testing on a small number of cycles shows that both models are good
describe experimental data, so scientists extrapolate the dependence
the accuracy of converting the chain from the number of cycles to a larger number of cycles.

Comparison of the time required to solve the problem on
classical and quantum processor, allowed scientists to compare how much
the problem becomes more difficult with an increase in the number of qubits. If with a task for 53
qubits, a classical computer coped in 15.9 days, then a 56-qubit
takes him 8.2 years.

Although the authors used two different algorithms
with significantly different approaches for simulations on a classic computer
and received close estimates, they foresee the emergence of new, more effective
algorithms. In their opinion, this will allow the competition between
classical and quantum computing and may be useful in
scaling quantum systems.

A simple and efficient classical algorithm for the simulation of quantum
circuits with the same architecture have already been proposed and implemented by a group of Chinese physicists.BUT
their colleagues showed that the photonic quantum processor is faster
classical in solving another problem.