switch Statement in C

The switch statement selects one branch from several constant choices. It is useful when one expression is compared against discrete values such as menu numbers, characters or status codes.

switch Syntax Top ↑

switch (expression) {
    case value1:
        // statements
        break;

    case value2:
        // statements
        break;

    default:
        // no case matched
        break;
}

case labels must be constant integral expressions. The optional default branch runs when no case matches.

Why break Matters Top ↑

Without break, execution continues into the following case. This behavior is called fall-through. Use it only when several cases intentionally share the same code.

Grade Example Top ↑

#include <stdio.h>

int main(void) {
    char grade;

    printf("Enter grade A to D: ");
    grade = (char)getchar();

    switch (grade) {
        case 'A':
            printf("You got A grade.\n");
            break;
        case 'B':
            printf("You got B grade.\n");
            break;
        case 'C':
            printf("You got C grade.\n");
            break;
        case 'D':
            printf("You got D grade.\n");
            break;
        default:
            printf("Unknown grade.\n");
            break;
    }

    return 0;
}

Grouping Multiple Cases Top ↑

Key change: several case labels can intentionally fall through to one shared statement block.

#include <stdio.h>

int main(void) {
    int day = 5;

    switch (day) {
        case 1:
        case 2:
        case 3:
        case 4:
        case 5:
            printf("It is a weekday.\n");
            break;
        case 6:
        case 7:
            printf("It is the weekend.\n");
            break;
        default:
            printf("Invalid day.\n");
            break;
    }

    return 0;
}

Output

It is a weekday.

Menu-Driven Calculator Top ↑

#include <stdio.h>

int main(void) {
    int num1, num2, choice;

    printf("Enter two integers: ");
    if (scanf("%d %d", &num1, &num2) != 2) {
        printf("Invalid input.\n");
        return 1;
    }

    printf("1. Add\n2. Subtract\n3. Multiply\n4. Divide\n");
    printf("Choose an operation: ");
    if (scanf("%d", &choice) != 1) {
        printf("Invalid choice.\n");
        return 1;
    }

    switch (choice) {
        case 1:
            printf("Result: %d\n", num1 + num2);
            break;
        case 2:
            printf("Result: %d\n", num1 - num2);
            break;
        case 3:
            printf("Result: %d\n", num1 * num2);
            break;
        case 4:
            if (num2 != 0) {
                printf("Result: %.2f\n", (double)num1 / num2);
            } else {
                printf("Cannot divide by zero.\n");
            }
            break;
        default:
            printf("Invalid choice.\n");
            break;
    }

    return 0;
}

switch or if...else? Top ↑

• Use switch for several exact integral/character choices.
• Use if...else for ranges, compound logical conditions and comparisons such as x > 10.

Subhendu Mohapatra

Author & Instructor at plus2net

I write and maintain practical tutorials on Python, PHP, SQL, JavaScript, HTML, jQuery, and web development at plus2net. The tutorials focus on clear explanations, working examples, and code that readers can test and adapt while learning.

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