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

You could do something like this at the end of your switch statement:

default:
    if(num < 0)
    {
        ... // Code
    }
    break;

Answer 2

I know that this topic is pretty old but if someone still looking for the answer now in C# 7 it's possible. Here is an example:

switch (value)
{
     case var expression when value < 0:
         //some code
         break; 

     case var expression when (value >= 0 && value < 5):
         //some code
         break;

     default:
         //some code
         break;
}

Answer 3

The only way I could think of (and I really don't recommand it), would be as follows:

int someValue;

switch (Math.Max(someValue, -1))
{
    case -1:
        // will be executed for everything lower than zero.
        break;

    case 0:
       // will be executed for value 0.
       break;

    case 1:
       // will be executed for value 1.
       break;

    default:
       // will be executed for anything else.
       break;
}

Answer 4

you can do this

switch (mark)
{
    case int n when n >= 80:
        Console.WriteLine("Grade is A");
        break;

    case int n when n >= 60:
        Console.WriteLine("Grade is B");
        break;

    case int n when n >= 40:
        Console.WriteLine("Grade is C");
        break;

    default:
        Console.WriteLine("Grade is D");
        break;
}

Answer 5

You cannot use comparisons in switches like you could in VB, you have 2 options here, replace the value you switch on with a known value and use that or - if you mean all other cases - you can use the default clause:

switch(num)
{
  case 4:
    // some code ;
    break;
  case 3:
    // some code ;
    break;
  case 0:
    // some code ;
    break;
  default:
    // some code ;
    break;
}

Note that this does not exactly like you asked for: any values other than 0,3,4 will end up in the deafult: clause.

Answer 6

I've run into the following pattern recently, and while I abhor it, I can't argue that it's not practical:

switch(0)
{
  case 0 when x < 0:
    ...
    break;
  case 0 when a > 5 && x == 0:
    ...
    break;
}

The use of dummy expressions ((0) in the switch, and case 0) is absolutely terrible, and I'd hate for it to become an idiom, but hey - it's concise and very clear. For sure it's not some hack that completely obscures the meaning and needs arcane knowledge, but C# would do well to obviate the need for it. I'd like the following to be legal:

switch                   // maybe () here, if the grammar would demand
{
  case when x < 0:       // I like the case to stay
    ...
  case when a > 5 && x == 0:
    ...
}