How to insert newline in string literal?

Well, simple options are:

• string.Format:

  string x = string.Format("first line{0}second line", Environment.NewLine);
  

• String concatenation:

  string x = "first line" + Environment.NewLine + "second line";
  

• String interpolation (in C#6 and above):

  string x = $"first line{Environment.NewLine}second line";
  

You could also use \n everywhere, and replace:

string x = "first line\nsecond line\nthird line".Replace("\n",
                                                         Environment.NewLine);

Note that you can’t make this a string constant, because the value of Environment.NewLine will only be available at execution time.