How do I interpolate strings?

Question

I want to do the following in C# (coming from a Python background):

strVar = \"stack\"
mystr  = \"This is %soverflow\" % (strVar)

How do I

Answer 1

This has been added as of C# 6.0 (Visual Studio 2015+).

Example:

var planetName = "Bob";
var myName = "Ford"; 
var formattedStr = $"Hello planet {planetName}, my name is {myName}!";
// formattedStr should be "Hello planet Bob, my name is Ford!"

This is syntactic sugar for:

var formattedStr = String.Format("Hello planet {0}, my name is {1}!", planetName, myName);

Additional Resources:

String Interpolation for C# (v2) Discussion

C# 6.0 Language Preview

Answer 2

Basic example:

        var name = "Vikas";
        Console.WriteLine($"My name is {name}");

Adding Special characters:

string name = "John";
Console.WriteLine($"Hello, \"are you {name}?\", but not the terminator movie one :-{{");
//output-Hello, "are you John?", but not the terminator movie one :-{

Not just replacing token with value, You can do a lot more with string interpolation in C#

Evaluating Expression

Console.WriteLine($"The greater one is: { Math.Max(10, 20) }");
//output - The greater one is: 20

Method call

    static void Main(string[] args)
    {
        Console.WriteLine($"The 5*5  is {MultipleByItSelf(5)}");
    }
  
    static int MultipleByItSelf(int num)
    {           
        return num * num;
    }

Source: String Interpolation in C# with examples

Answer 3

You can accomplish this with Expansive: https://github.com/anderly/Expansive

Answer 4

There's one more way to implement placeholders with string.Replace, oddly helps in certain situations:

mystr = mystr.Replace("%soverflow", strVar);

Answer 5

If you currently use Visual Studio 2015 with C# 6.0, try the following:

var strVar = "stack";

string str = $"This is {strVar} OverFlow";

that feature is called string interpolation.

Answer 6

There is no operator for that. You need to use string.Format.

string strVar = "stack";
string mystr  = string.Format("This is {0}soverflow", strVar);

Unfortunately string.Format is a static method, so you can't simply write "This is {0}soverflow".Format(strVar). Some people have defined an extension method, that allows this syntax.