The switch statement

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

The switch statement

switch picks one of several cases based on the value of an expression. Each case starts with case and ends with break. If none matches, default runs.

int day = 3;
switch (day) {
    case 1: printf("Monday\n"); break;
    case 2: printf("Tuesday\n"); break;
    case 3: printf("Wednesday\n"); break;
    default: printf("Unknown\n");
}

switch only works with integer or char values; it cannot use strings. Each case is a label; when a match is found, flow starts there.

Fall-through behavior

Without break, flow falls through to the next case. Sometimes this is wanted; usually it's a bug.

int n = 1;
switch (n) {
    case 1:
    case 2:
    case 3:
        printf("1-3 range\n");
        break;
    default:
        printf("Outside\n");
}

Here case 1, case 2 and case 3 share the same block. For n=1, n=2 and n=3 you get the same output.

Exercise Print the season with switch

Write a C program. Declare int month = 4;. Use switch (month) to print the season: for case 12, case 1, case 2 print printf("Winter\n"); break;, for case 3, case 4, case 5 print printf("Spring\n"); break;, for default print printf("Other\n");. Put #include <stdio.h> at the top.

Show example solution

#include <stdio.h>

int main(void) {
    int month = 4;
    switch (month) {
        case 12: case 1: case 2:
            printf("Winter\n");
            break;
        case 3: case 4: case 5:
            printf("Spring\n");
            break;
        default:
            printf("Other\n");
    }
    return 0;
}

Test yourself

Match the switch parts

switch

Main statement
case

Case label
break

Stop
default

Fallback
What does break do in a switch?
```
case 1: printf("A"); break;
```
- Goes to the default case
- Starts a new case
- Exits the switch block
- Nothing
Show answer

Exits the switch block — break exits the switch block.

Close the switch

switch (n) {
    case 1: printf("A"); break;
    default: printf("Unknown");
____;

Show answer

switch (n) {
    case 1: printf("A"); break;
    default: printf("Unknown");
};

Next lesson: The ternary operator

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