Evaluate Expressions in Switch Statements in C#

Question

I have to implement the following in a switch statement:

switch(num)
{
  case 4:
    // some code ;
    break;
  case 3:
    // some code ;
    brea         


        

Answer 1

In twist of C# fate, this has come all the way back around. If you upgrade to C# 9.0, your original switch statement will now compile! C#9.0 has added Relational patterns to pattern matching in general, which includes switch statements.

You can now do some really funky stuff, like this:

      var num = new Random().Next();
      
      switch(num)
      {
        case < 0:
          // some code ;
          break;
        case 0:
          // some code ;
          break;
        case > 0 and < 10:
          // some code ;
          break;
        case > 20 or (< 20 and 15):
          // some code ;
          break;
      }

Note the use of literal 'and' and 'or' in the last case, to allow && and || type expressions to compile.

To use C# 9, make sure the XmlNode LangVersion is set to Latest or 9.0 in the csproj file, in a property group

e.g.

  
    netstandard2.0
    AnyCPU;x86
    Debug;Release;Mock
    Latest