Scala has triple quoted strings `&quot;&quot;&quot;String\nString&quot;&quot;&quot;` to use special characters in the string without escaping. Scala 2.10 also added `raw&quot;String\nString&quot;` for the same purpose.

Is there any difference in how `raw&quot;&quot;` and `&quot;&quot;&quot;&quot;&quot;&quot;` work? Can they produce different output for the same string?

What&#39;s the difference between raw string interpolation and triple quotes in scala

I want to create a string with embedded information.  One way (not the only way) of achieving what I want is called [string interpolation][1] or variable substitution, wherein placeholders in a string are replaced with actual values.

In C, I would do something like this:

&lt;!-- language: lang-c --&gt;

    printf(&quot;error! value was %d but I expected %d&quot;,actualValue,expectedValue)

whereas if I were programming in python, I would do something like this:

&lt;!-- language: lang-python --&gt;

    &quot;error! value was {0} but I expected {1}&quot;.format(actualValue,expectedValue)

both of these are examples of string interpolation.

How can I do this in C++?

**Important Caveats**:

1. I know that I can use ``std::cout`` if I want to print such a message to standard output (not string interpolation, but prints out the kind of string I want):

&lt;!-- language: lang-c++ --&gt;

    cout &lt;&lt; &quot;error! value was &quot; &lt;&lt; actualValue &lt;&lt; &quot; but I expected &quot;
    &lt;&lt; expectedValue;

I don&#39;t want to *print* a string to stdout.  I want to pass a `std::string` as an argument to a function (e.g. the constructor of an exception object).

2. I am using C++11, but portability is potentially an issue, so knowing which methods work and don&#39;t work in which versions of C++ would be a plus.

**Edit**

3. For my immediate usage, I&#39;m not concerned about performance (I&#39;m raising an exception for cryin&#39; out loud!).  *However*, knowing the relative performance of the various methods would be very very useful in general.

4. Why not just use printf itself (C++ is a superset of C after all...)?  [This answer][2] discusses some reasons why not.  As far as I can understand, type safety is a big reason: if you put %d, the variable you put in there had better really be convertible to an integer, as that&#39;s how the function figures out what type it is.  It would be much safer to have a method which uses compile-time knowledge of the actual type of the variables to be inserted.


  [1]: https://en.wikipedia.org/wiki/String_interpolation
  [2]: https://stackoverflow.com/a/2872576/407588

How to construct a std::string with embedded values, i.e. &quot;string interpolation&quot;?

In Groovy, I have a multiline String, defined with `&#39;&#39;&#39;`, in which I need to use interpolation in order to substitute some other variables.

For all my efforts, I can&#39;t get it to work -- I assume I need to escape something, which I&#39;m missing. 

Here&#39;s some sample code:

    def cretanFood = &quot;Dakos&quot; 
    def mexicanFood = &quot;Tacos&quot;
    def bestRestaurant = &#39;&#39;&#39; 
    ${mexicanFood} &amp; ${cretanFood}
    &#39;&#39;&#39;
    print bestRestaurant


At the moment, this outputs: 

    ${mexicanFood} &amp; ${cretanFood}

while I would clearly expect: 

    Tacos &amp; Dakos 

(Note - I would prefer not to concatenate the strings)


How do I use String interpolation in a Groovy multiline string?

In Ruby I could do this.

    aaa = &quot;AAA&quot;
    bbb = &quot;BBB #{aaa}&quot;

    puts(bbb)
    
    &gt; &quot;BBB AAA&quot;

The point of this syntax is eliminating repetition, and making it to feel like a shell script - great for heavy string manipulation.

Does Rust support this? Or have plan to support this? Or have some feature which can mimic this?

Does Rust support Ruby-like string interpolation?

I always used the following syntax to be sure that variable were expanded in a string:

`&quot;my string with a $($variable)&quot;`

I recently ran into the following syntax:

`&quot;my string with a ${variable}&quot;`

Are they equivalent? Any difference?

PowerShell string interpolation syntax

String interpolation is [available in Scala][1] starting Scala 2.10 

This is the basic example 


     val name = &quot;World&quot;            //&gt; name  : String = World
     val message = s&quot;Hello $name&quot;  //&gt; message  : String = Hello World

I was wondering if there is a way to do dynamic interpolation, e.g. the following (doesn&#39;t compile, just for illustration purposes)

     val name = &quot;World&quot;            //&gt; name  : String = World
     val template = &quot;Hello $name&quot;  //&gt; template  : String = Hello $name
     //just for illustration:
     val message = s(template)     //&gt; doesn&#39;t compile (not found: value s)



1. Is there a way to &quot;dynamically&quot; evaluate a String like that? (or is it inherently wrong / not possible)

2. And what is `s` exactly? &lt;del&gt;it&#39;s not a method def&lt;/del&gt; ([apparently it is a method on `StringContext`][2]), and not an object (if it was, it would have thrown a different compile error than *not found* I think)


----------

  [1]: http://docs.scala-lang.org/overviews/core/string-interpolation.html
  [2]: http://www.scala-lang.org/files/archive/nightly/docs/library/index.html#scala.StringContext@s(args:Any*):String

String interpolation in Scala 2.10 - How to interpolate a String variable?

In C# 6 what is the default culture for the new string interpolation?

I&#39;ve seen conflicting reports of both Invariant and Current Culture.

I would like a definitive answer and I&#39;m keeping my fingers crossed for Invariant.

What is the default culture for C# 6 string interpolation?

String building in Java confounds me. I abhore doing things like:

    url += &quot;u1=&quot; + u1 + &quot;;u2=&quot; + u2 + &quot;;u3=&quot; + u3 + &quot;;u4=&quot; + u4 + &quot;;&quot;;
    url += &quot;x=&quot; + u1 + &quot;;y=&quot; + u2 + &quot;;z=&quot; + u3 + &quot;;da1=&quot; + u4 + &quot;;&quot;;
    url += &quot;qty=1;cost=&quot; + orderTotal + &quot;;ord=&quot; + orderId + &quot;?&quot;;

Or, using StringBuilder, something like this:

		url.append(&quot;u1=&quot;);
		url.append(u1);
		url.append(&quot;;u2=&quot;);
		url.append(u2);
		url.append(&quot;;u3=&quot;);
		url.append(u3);
		url.append(&quot;;u4=&quot;);
		url.append(u4);
		url.append(&quot;;&quot;);
		url.append(&quot;x=&quot;);
		url.append(u1);
		url.append(&quot;;y=&quot;);
		url.append(u2);
		url.append(&quot;;z=&quot;);
		url.append(u3);
		url.append(&quot;;da1=&quot;);
		url.append(u4);
		url.append(&quot;;&quot;);
		url.append(&quot;qty=1;&quot;);
		url.append(&quot;cost=&quot;);
		url.append(orderTotal);
		url.append(&quot;;ord=&quot;);
		url.append(orderId);
		url.append(&quot;?&quot;);

SURELY I&#39;m missing something. There has GOT to be a better way. Something like:

Instead of:

    urlString += &quot;u1=&quot; + u1 + &quot;;u2=&quot; + u2 + &quot;;u3=&quot; + u3 + &quot;;u4=&quot; + u4 + &quot;;&quot;;

do:

    urlString += Interpolator(&quot;u1=%s;u2=%s;u3=%s;u4=%s;&quot;, u1, u2, u3, u4);

or:

    urlStringBuilder.append(Interpolator(&quot;u1=%s;u2=%s;u3=%s;u4=%s;&quot;, u1, u2, u3, u4));

String variable interpolation Java

C# uses string interpolation
 
    int value = 100;
    Console.WriteLine($&quot;The size is {value}.&quot;);

Output:

&gt;The size is 100.

How to do the same thing in TypeScript?

How to perform string interpolation in TypeScript?

In C# 6 there is a new feature: interpolated strings. These let you put expressions directly into code.

Rather than relying on indexes:

    string s = string.Format(&quot;Adding \&quot;{0}\&quot; and {1} to foobar.&quot;, x, this.Y());

the above becomes:

    string s = $&quot;Adding \&quot;{x}\&quot; and {this.Y()} to foobar.&quot;;

However, we have a lot of strings across multiple lines using verbatim strings (mainly SQL statements) like this:

    string s = string.Format(@&quot;Result...
    Adding &quot;&quot;{0}&quot;&quot; and {1} to foobar:
    {2}&quot;, x, this.Y(), x.GetLog());

Reverting these to regular strings seems messy:

    string s = &quot;Result...\r\n&quot; +
    $&quot;Adding \&quot;{x}\&quot; and {this.Y()} to foobar:\r\n&quot; +
    x.GetLog().ToString();

How to use both verbatim and interpolated strings together?

How to use verbatim strings with interpolation?

Consider this code:

    var age = 3;
    
    console.log(&quot;I&#39;m &quot; + age + &quot; years old!&quot;);

Are there any other ways to insert the value of a variable in to a string, apart from string concatenation?

How can I do string interpolation in JavaScript?

I am using template strings to generate some files and I love the conciseness of the new f-strings for this purpose, for reducing my previous template code from something like this:
     
    template_a = &quot;The current name is {name}&quot;
    names = [&quot;foo&quot;, &quot;bar&quot;]
    for name in names:
        print (template_a.format(**locals()))

Now I can do this, directly replacing variables:

    names = [&quot;foo&quot;, &quot;bar&quot;]
    for name in names:
        print (f&quot;The current name is {name}&quot;)

However, sometimes it makes sense to have the template defined elsewhere — higher up in the code, or imported from a file or something. This means the template is a static string with formatting tags in it. Something would have to happen to the string to tell the interpreter to interpret the string as a new f-string, but I don&#39;t know if there is such a thing.

**Is there any way to bring in a string and have it interpreted as an f-string to avoid using the `.format(**locals())` call?**

Ideally I want to be able to code like this... (where `magic_fstring_function` is where the part I don&#39;t understand comes in):

    template_a = f&quot;The current name is {name}&quot;
    # OR [Ideal2] template_a = magic_fstring_function(open(&#39;template.txt&#39;).read())
    names = [&quot;foo&quot;, &quot;bar&quot;]
    for name in names:
        print (template_a)

...with this desired output (without reading the file twice):

&lt;!-- language: lang-none --&gt;

    The current name is foo
    The current name is bar

...but the actual output I get is:

&lt;!-- language: lang-none --&gt;

    The current name is {name}
    The current name is {name}

How to postpone/defer the evaluation of f-strings?

Is there a noticable performance difference between using string interpolation:

    myString += $&quot;{x:x2}&quot;;

vs String.Format()?

    myString += String.Format(&quot;{0:x2}&quot;, x);

I am only asking because Resharper is prompting the fix, and I have been fooled before.

String Interpolation vs String.Format

How do I escape a dollar sign in string interpolation?

    def getCompanion(name: String) = Class.forName(s&quot;my.package.$name\$&quot;)
    
    // --&gt; &quot;error: unclosed string literal&quot;

Escape a dollar sign in string interpolation

I have the following code:

    $DatabaseSettings = @();
    $NewDatabaseSetting = &quot;&quot; | select DatabaseName, DataFile, LogFile, LiveBackupPath;
    $NewDatabaseSetting.DatabaseName = &quot;LiveEmployees_PD&quot;;
    $NewDatabaseSetting.DataFile = &quot;LiveEmployees_PD_Data&quot;;
    $NewDatabaseSetting.LogFile = &quot;LiveEmployees_PD_Log&quot;;
    $NewDatabaseSetting.LiveBackupPath = &#39;\\LiveServer\LiveEmployeesBackups&#39;;
    $DatabaseSettings += $NewDatabaseSetting;

When I try to use one of the properties in a string execute command:

    &amp; &quot;$SQlBackupExePath\SQLBackupC.exe&quot; -I $InstanceName -SQL `
      &quot;RESTORE DATABASE $DatabaseSettings[0].DatabaseName FROM DISK = &#39;$tempPath\$LatestFullBackupFile&#39; WITH NORECOVERY, REPLACE, MOVE &#39;$DataFileName&#39; TO &#39;$DataFilegroupFolder\$DataFileName.mdf&#39;, MOVE &#39;$LogFileName&#39; TO &#39;$LogFilegroupFolder\$LogFileName.ldf&#39;&quot;

It tries to just use the value of `$DatabaseSettings` rather than the value of `$DatabaseSettings[0].DatabaseName`, which is not valid.  
My workaround is to have it copied into a new variable.

How can I access the object&#39;s property directly in a double-quoted string?

How can you use an object&#39;s property in a double-quoted string?

I have several text files in which I have introduced shell variables ($VAR1 or $VAR2 for instance).

I would like to take those files (one by one) and save them in new files where all variables would have been replaced.

To do this, I used the following shell script (found on StackOverflow):

    while read line
    do
        eval echo &quot;$line&quot; &gt;&gt; destination.txt
    done &lt; &quot;source.txt&quot;

This works very well on very basic files.

But on more complex files, the &quot;eval&quot; command does too much:

- Lines starting with &quot;#&quot; are skipped

- XML files parsing results in tons of errors

Is there a better way to do it? (in shell script... I know this is easily done with Ant for instance)

Kind regards


How to substitute shell variables in complex text files

I know in PHP we can do something like this:

    $hello = &quot;foo&quot;;
    $my_string = &quot;I pity the $hello&quot;;

Output: `&quot;I pity the foo&quot;`

I was wondering if this same thing is possible in JavaScript as well. Using variables inside strings without using concatenation — it looks more concise and elegant to write.


How to interpolate variables in strings in JavaScript, without concatenation?

I want to do the following in C# (coming from a Python background):

    strVar = &quot;stack&quot;
    mystr  = &quot;This is %soverflow&quot; % (strVar)

How do I replace the token inside the string with the value outside of it?

How do I interpolate strings?

Since beta 8.3, zillions warnings &quot;String interpolation produces a debug description for an optional value; did you mean to make this explicit?&quot; appeared in my code.

For example, the warning popped in the following situation up, where options could lead to nil:

    let msg = &quot;*** Error \(options[&quot;taskDescription&quot;]): cannot load \(sUrl) \(error)&quot;

As previously designed, it was ok for me (and the compiler) the optionals to be interpolated as &#39;nil&#39;. But compiler changed its mind.

What the compiler suggests is to add a String constructor with description as follows:

    let msg = &quot;*** Error \(String(describing: options[&quot;taskDescription&quot;])): cannot load \(sUrl) \(error)&quot;

Obviously, the results is explicit but also very very cumbersome in my opinion. Is there a better option? Do I have to fix all those warning or better wait for the next beta?

[![Screenshot for description][1]][1]


  [1]: https://i.stack.imgur.com/llT41.png

How to solve &quot;String interpolation produces a debug description for an optional value; did you mean to make this explicit?&quot; in Xcode 8.3 beta?

I&#39;m confused as to why this code won&#39;t compile:

    var result = $&quot;{fieldName}{isDescending ? &quot; desc&quot; : string.Empty}&quot;;

If I split it up, it works fine:

    var desc = isDescending ? &quot; desc&quot; : string.Empty;
    var result = $&quot;{fieldName}{desc}&quot;;

How to use the ternary operator inside an interpolated string?

I&#39;ve been using string interpolation and love it. However, I have an issue where I am trying to include a backslash in my output, but I am not able to get it to work.

I want something like this...

    var domain = &quot;mydomain&quot;;
    var userName = &quot;myUserName&quot;;
    var combo = $&quot;{domain}\{userName}&quot;

I want the output of *combo* to be:

    myDomain\myUserName

I get a syntax error about the \ being an escape character. If I put in \\\ then the syntax error is gone, but the output is *myDomain\\\myUsername*.

How can I include escaped characters in an interpolated string?






How can I use escape characters with string interpolation in C# 6?

C# 6 brings compiler support for interpolated string literals with syntax:

    var person = new { Name = &quot;Bob&quot; };

    string s = $&quot;Hello, {person.Name}.&quot;;

This is great for short strings, but if you want to produce a longer string must it be specified on a single line?

With other kinds of strings you can:

        var multi1 = string.Format(@&quot;Height: {0}
    Width: {1}
    Background: {2}&quot;,
            height,
            width,
            background);

Or:

    var multi2 = string.Format(
        &quot;Height: {1}{0}&quot; +
        &quot;Width: {2}{0}&quot; +
        &quot;Background: {3}&quot;,
        Environment.NewLine,
        height,
        width,
        background);

I can&#39;t find a way to achieve this with string interpolation without having it all one one line:

    var multi3 = $&quot;Height: {height}{Environment.NewLine}Width: {width}{Environment.NewLine}Background: {background}&quot;;

I realise that in this case you could use `\r\n` in place of `Environment.NewLine` (less portable), or pull it out to a local, but there will be cases where you can&#39;t reduce it below one line without losing semantic strength.

Is it simply the case that string interpolation should not be used for long strings?

Should we just string using `StringBuilder` for longer strings?

    var multi4 = new StringBuilder()
        .AppendFormat(&quot;Width: {0}&quot;, width).AppendLine()
        .AppendFormat(&quot;Height: {0}&quot;, height).AppendLine()
        .AppendFormat(&quot;Background: {0}&quot;, background).AppendLine()
        .ToString();

Or is there something more elegant?

Multiline C# interpolated string literal

I have used interpolated strings for messages containing `string` variables like `$&quot;{EmployeeName}, {Department}&quot;`. Now I want to use an interpolated string for showing a formatted `double`.

Example

    var aNumberAsString = aDoubleValue.ToString(&quot;0.####&quot;);

How can I write it as an interpolated string? Something like `$&quot;{aDoubleValue} ....&quot;`

C# 6 how to format double using interpolated string?

Are variables within YAML files possible? For example:

    theme:
      name: default
      css_path: compiled/themes/$theme.name
      layout_path: themes/$theme.name

In this example, how can `theme: name: default` be used in other settings? What is the syntax?

Use YAML with variables

The proper way to use string interpolation in Ruby is as follows:

    name = &quot;Ned Stark&quot;
    puts &quot;Hello there, #{name}&quot; #=&gt; &quot;Hello there, Ned Stark&quot;

That is the way I intend to always use it. 

However, I&#39;ve noticed something **odd** in Ruby&#39;s string interpolation. I&#39;ve noticed that string interpolation works in Ruby without the curly braces in regards to instance variables. For example:

    @name = &quot;Ned Stark&quot;
    puts &quot;Hello there, #@name&quot; #=&gt; &quot;Hello there, Ned Stark&quot;

And that trying the same thing as a non-instance variable does not work.

    name = &quot;Ned Stark&quot;
    puts &quot;Hello, there, #name&quot; #=&gt; &quot;Hello there, #name&quot;

I&#39;ve tried this with success in both 1.9.2 and 1.8.7. 

Why does this work? What is the interpreter doing here?

Why does string interpolation work in Ruby when there are no curly braces?

In PHP I am trying to create a newline character:

    echo $clientid;
    echo &#39; &#39;;
    echo $lastname;
    echo &#39; &#39;;
    echo &#39;\r\n&#39;;

Afterwards I open the created file in Notepad and it writes the newline literally:

&gt; 1 John Doe\r\n 1 John Doe\r\n 1 John Doe\r\n

I have tried many variations of the `\r\n`, but none work.  Why isn&#39;t the newline turning into a newline?

PHP - how to create a newline character?

I am just starting to learn Ruby (first time programming), and have a basic syntactical question with regards to variables, and various ways of writing code. 

Chris Pine&#39;s &quot;Learn to Program&quot; taught me to write a basic program like this...

    num_cars_again= 2
    puts &#39;I own &#39; + num_cars_again.to_s + &#39; cars.&#39;

This is fine, but then I stumbled across the tutorial on ruby.learncodethehardway.com, and was taught to write the same exact program like this...

    num_cars= 2
    puts &quot;I own #{num_cars} cars.&quot;


They both output the same thing, but obviously option 2 is a much shorter way to do it. 

Is there any particular reason why I should use one format over the other?



String concatenation vs. interpolation in Ruby

I&#39;m using the `.format()` a lot in my Python 3.5 projects, but I&#39;m afraid that it will be deprecated during the next Python versions because of f-strings, the new kind of string literal.

    &gt;&gt;&gt; name = &quot;Test&quot;
    &gt;&gt;&gt; f&quot;My app name is {name}.&quot;
    &#39;My app name is Test.&#39;

Does the formatted string feature come to fully replace the old `.format()`? And from now on, would it be better to use the new style in all cases?

I understand that it&#39;s based on the idea that &quot;Simple is better than complex.&quot; However, what about performance issues; is there any difference between them? Or is it just a simple look of the same feature?

f-strings vs str.format()

Why are **implicitly unwrapped optionals** not unwrapped when using string interpolation in Swift 3?

**Example**:
Running the following code in the playground

    var str: String!
    str = &quot;Hello&quot;
    
    print(&quot;The following should not be printed as an optional: \(str)&quot;)

produces this output: 

    The following should not be printed as an optional: Optional(&quot;Hello&quot;)

Of course I can concatenate strings with the `+` operator but I&#39;m using string interpolation pretty much everywhere in my app which now doesn&#39;t work anymore due to this (bug?). 

Is this even a bug or did they intentionally change this behaviour with Swift 3?

Swift 3 incorrect string interpolation with implicitly unwrapped Optionals

I have recently been learning python 3 and I cannot get any examples involving string interpolation (formatting) to work. 

    In [1]: state = &quot;Washington&quot;

    In [2]: state
    Out[2]: &#39;Washington&#39;

    In [3]: my_message = f&quot;I live in {state}&quot;
    File &quot;&lt;ipython-input-3-d004dd9e0255&gt;&quot;, line 1
    my_message = f&quot;I live in {state}&quot;
                                    ^
    SyntaxError: invalid syntax

I figured my machine was defaulting to python 2, but a quick check reveals:

    Python 3.5.2 (default, Nov 17 2016, 17:05:23) 
    Type &quot;copyright&quot;, &quot;credits&quot; or &quot;license&quot; for more information.

    IPython 5.2.2 -- An enhanced Interactive Python.

I am on Ubuntu 16.04:
    
    python3 --version
    Python 3.5.2

Am I just overlooking basic syntax? I have run the same commands on a few computers from fellow students and it seems to execute just fine.



Getting an &quot;invalid syntax&quot; when trying to perform string interpolation

What is the difference between the two following methods (performance, readability, etc.) and what do you prefer?

    echo &quot;Welcome {$name}s!&quot;

vs.

    echo &quot;Welcome &quot; . $name . &quot;!&quot;;


PHP variable interpolation vs concatenation

Ruby example:

    name = &quot;Spongebob Squarepants&quot;
    puts &quot;Who lives in a Pineapple under the sea? \n#{name}.&quot;
The successful Python string concatenation is seemingly verbose to me.


  [1]: http://stackoverflow.com/questions/4450592/string-interpolation-in-python/4450610#4450610
  [2]: http://stackoverflow.com/users/279627/sven-marnach
  [3]: http://stackoverflow.com/users/543475/einlama

Is there a Python equivalent to Ruby&#39;s string interpolation?

I tried to use the conditional operator inside an interpolated string, but because it has a colon in it, the compiler thinks that after the colon comes a format string.

    $&quot;test {foo ? &quot;foo is true&quot; : &quot;foo is false&quot;}&quot;;

How can I use this type of statement?
The only thing that comes to my mind is something like this:

    var fooString = foo ? &quot;foo is true&quot; : &quot;foo is false&quot;;
    $&quot;test {fooString}&quot;;

C# interpolated string with conditional-operator

I&#39;m looking for a formatted byte string literal. Specifically, something equivalent to

    name = &quot;Hello&quot;
    bytes(f&quot;Some format string {name}&quot;)

Possibly something like `fb&quot;Some format string {name}&quot;`.

Does such a thing exist?

Is there a formatted byte string literal in Python 3.6+?

String interpolation in C#6 lets me write:

    decimal m = 42.0m;
    string x = $&quot;The value is {m}&quot;;

However, a very common use case for string formatting is to specify the locale used for formatting the values. Let&#39;s say I need to use `InvariantCulture` for the formatting operation above, what is the syntax for that ? 

[This discussion][1] suggests that I should be able to do this:
    
    string x = INV($&quot;The value is {m}&quot;);

Where INV is defined as

    public static string INV(IFormattable formattable)
    {
        return formattable.ToString(null, System.Globalization.CultureInfo.InvariantCulture);
    }

However, this does not work. It compiles, but it leaves my program hanging at in cmd.exe at startup - as if klr.exe, that I assume is being invoked, hangs (Compiler bug?)

This is an ASP.NET 5 Console Project in VS15 CTP 6.

  [1]: https://roslyn.codeplex.com/discussions/570292

All String Interpolation Solutions on Gang of Coders

Total of 35 String Interpolation Solutions

What's the difference between raw string interpolation and triple quotes in scala

How to construct a std::string with embedded values, i.e. "string interpolation"?