How add "or" in switch statements?

Question

This is what I want to do:

switch(myvar)
{
    case: 2 or 5:
    ...
    break;

    case: 7 or 12:
    ...
    break;
    ...
}

I tried with "case: 2 || 5" ,but it didn't work.

The purpose is to not write same code for different values.

Ambulant

What do you mean "it didn't work"? Does it give you syntax errors, or logical errors? – Cervine

Starting with C# 9, this exact syntax is allowed. – Sedentary

Answer 1

By stacking each switch case, you achieve the OR condition.

switch(myvar)
{
    case 2:
    case 5:
    ...
    break;

    case 7:
    case 12:
    ...
    break;
    ...
}

Transcendent

Joel, it doesn't support fall through but it DOES support stacking (e.g., an empty case 2 in this answer executes the case 5 section). – Godless

This was exactly what I was looking for. Good job, your work is appreciated. – Simulacrum

Answer 2

You do it by stacking case labels:

switch(myvar)
{
    case 2:
    case 5:
    ...
    break;

    case 7: 
    case 12:
    ...
    break;
    ...
}

Slowwitted

Answer 3

You may do this as of C# 9.0:

switch(myvar)
{
    case 2 or 5:
        // ...
        break;

    case 7 or 12:
        // ...
        break;
    // ...
}

Jo

This is more readable then allowing it fall through, downside it's C# 9.0 up only as you pointed out. – Christoffer

Answer 4

case 2:
case 5:
do something
break;

Selfcommand

Answer 5

Case-statements automatically fall through if you don't specify otherwise (by writing break). Therefor you can write

switch(myvar)
{
   case 2:
   case 5:
   {
      //your code
   break;
   }

// etc... }

Tadashi

Note that this is only true for empty cases. Cases with actual body do not automatically fall through. – Selfcommand

Answer 6

Since C# 8 there are switch expressions that are better readable: no case, : and break;/return needed anymore. Combined with C# 9's logical patterns:

static string GetCalendarSeason(DateTime date) => date.Month switch
{
    3 or 4 or 5 => "spring",
    6 or 7 or 8 => "summer",
    9 or 10 or 11 => "autumn",
    12 or 1 or 2 => "winter",
    _ => throw new ArgumentOutOfRangeException(nameof(date), $"Date with unexpected month: {date.Month}."),
};

Limitation: with this syntax, at the right of the => you cannot use curly braces ({ and }) for statements.

Bisexual

Answer 7

The example for switch statement shows that you can't stack non-empty cases, but should use gotos:

// statements_switch.cs
using System;
class SwitchTest 
{
   public static void Main()  
   {
      Console.WriteLine("Coffee sizes: 1=Small 2=Medium 3=Large"); 
      Console.Write("Please enter your selection: "); 
      string s = Console.ReadLine(); 
      int n = int.Parse(s);
      int cost = 0;
      switch(n)       
      {         
         case 1:   
            cost += 25;
            break;                  
         case 2:            
            cost += 25;
            goto case 1;           
         case 3:            
            cost += 50;
            goto case 1;             
         default:            
            Console.WriteLine("Invalid selection. Please select 1, 2, or3.");            
            break;      
       }
       if (cost != 0)
          Console.WriteLine("Please insert {0} cents.", cost);
       Console.WriteLine("Thank you for your business.");
   }
}

Internationalist

-1 The msdn link has a stacked example further down the page. At any rate, stacked cases work, especially in this question where the stated purpose is to not write duplicate code as done in your case 1 and 2. – Codding

Usefull answer as example of "goto case". – Chantellechanter

I hate goto statements what is this 1992? – Cicily