Switch Statement in C

About this page

This is a tutorial in C Controls — switch, case, break, and fall-through behaviour. For runnable examples, see Switch Case Example Program and Weekdays Switch Program.

Introduction

The switch statement selects one of many code branches based on the value of an integer expression. It is cleaner than a long if-else-if chain when comparing one variable against many constant values.

Syntax

switch (expression) {
    case constant1:
        /* statements */
        break;
    case constant2:
        /* statements */
        break;
    default:
        /* optional — runs if no case matches */
        break;
}

Example — Weekday Name

#include <stdio.h>

int main(void) {
    int day = 3;

    switch (day) {
        case 1: printf("Monday\n");    break;
        case 2: printf("Tuesday\n");   break;
        case 3: printf("Wednesday\n"); break;
        case 4: printf("Thursday\n");  break;
        case 5: printf("Friday\n");    break;
        case 6: printf("Saturday\n");  break;
        case 7: printf("Sunday\n");    break;
        default: printf("Invalid day\n");
    }

    return 0;
}

Sample Output

Wednesday

The break Statement

break exits the switch immediately. Without it, execution falls through to the next case:

switch (ch) {
    case 'a':
    case 'e':
    case 'i':
    case 'o':
    case 'u':
        printf("Vowel\n");
        break;
    default:
        printf("Consonant or other\n");
}

Fall-through is intentional here — multiple cases share one block.

switch vs if-else-if

Best Practices

• Always include break unless fall-through is intentional (add a comment).
• Include a default case to handle unexpected values.
• Keep case bodies short — call a function for complex logic.
• Group related cases without break between them.

Common Mistakes

• Missing break causing unintended fall-through.
• Using non-constant expressions in case labels.
• Testing floating-point values with switch (not allowed in C).

Related Programs

See Switch Case Example Program and Weekdays Switch Program.