The switch statement

C# course · Beginner · Lesson 38/116

Learn multi-way selection with switch, case, break and default.

The switch statement

To select among many branches based on a single value you use switch. switch (day) takes the value and each case label compares it to a possible value. You exit the branch with break.

If no case matches, the default branch runs. switch reads better than a long else if chain, especially when selecting on enum or integer values.

break and fall-through

C# has no automatic fall-through between case branches; each branch must end with break (or return, goto). This prevents accidental fall-through bugs.

To send multiple values to the same block you can stack case labels: case 1:\ncase 2: Console.WriteLine("small"); break;. Here 1 and 2 produce the same output; this only works for a shared block.

Exercise Turn a day number into a name

Declare a day variable with the value 3. Use switch on day: case 1 prints "monday", case 2 "tuesday", case 3 "wednesday", and default prints "unknown". Use break in each case.

Show example solution

Open switch (day), write case 1/2/3 and default branches each ending with break.
Example solution:
using System;

class Program
{
    static void Main()
    {
        int day = 3;
        switch (day)
        {
            case 1:
                Console.WriteLine("monday");
                break;
            case 2:
                Console.WriteLine("tuesday");
                break;
            case 3:
                Console.WriteLine("wednesday");
                break;
            default:
                Console.WriteLine("unknown");
                break;
        }
    }
}

Test yourself

Match each switch part to its meaning

switch

Takes the value
case

A possible value
break

Exits the branch
default

When none match
What does 'case 1: case 2: Console.WriteLine("x"); break;' do in a switch?
```
switch (n) {
  case 1:
  case 2:
    Console.WriteLine("x");
    break;
}
```
- Prints 'x' only for n=1
- Prints 'x' for both n=1 and n=2
- Raises a compile error
- Prints nothing
Show answer

Prints 'x' for both n=1 and n=2 — Correct. Empty case labels stacked together share the same block.

Start the default branch

switch (code)
{
    case 1:
        Console.WriteLine("one");
        break;
    ____:
        Console.WriteLine("unknown");
        break;
}

Show answer

switch (code)
{
    case 1:
        Console.WriteLine("one");
        break;
    default:
        Console.WriteLine("unknown");
        break;
}

The switch statement