I'm trying to use a variable inside of an interpolated string, but not having much luck. How would I do this?

var name = "mike";

var desc = "hello world {name}";

var t = $"{ desc }";

Console.WriteLine(t); // PRINTS: hello world {name}

This is what I am trying to achieve:

Console.WriteLine(t); // PRINTS: hello world mike

Is this possible?

For example, suppose I have a method:

public string FormatString(string s) {

      var Now = DateTime.Now;

      return $s;

}

Usage:

Console.WriteLine(FormatString("The time is {Now}"));

You are missing a $

var name = "mike";

var desc = $"hello world {name}"; // this needs be interpolated as well

var t = $"{desc}";

Console.WriteLine(t); // PRINTS: hello world mike

Additional Resources

$ - string interpolation (C# Reference)

The $ special character identifies a string literal as an interpolated
string. An interpolated string is a string literal that might contain
interpolated expressions. When an interpolated string is resolved to a
result string, items with interpolated expressions are replaced by the
string representations of the expression results. This feature is
available in C# 6 and later versions of the language.

Update

but suppose I want to have a variable storing the string with {name}
in it. Is there no way to achieve interpolation if its in a variable?

No you would have to use standard String.Format Tokens

var tokenString = "Something {0}";



String.Format(tokenString,someVariable); 

String.Format Method

Converts the value of objects to strings based on the formats
specified and inserts them into another string.

Use String.Format if you need to insert the value of an object,
variable, or expression into another string. For example, you can
insert the value of a Decimal value into a string to display it to the
user as a single string:

Composite Formatting

The .NET composite formatting feature takes a list of objects and a
composite format string as input. A composite format string consists
of fixed text intermixed with indexed placeholders, called format
items, that correspond to the objects in the list. The formatting
operation yields a result string that consists of the original fixed text intermixed with the string representation of the objects in the list.