C - Switch Statement

switch selects a branch based on the value of an integral expression (e.g., int, char). Use it when comparing a single variable to many constants.

Learning Objectives

• Use switch with case, break, and default.
• Understand fall-through and when it’s intentional.

Prerequisites

• C - Conditional Statements

Example

#include <stdio.h>

int main(void) {
    char op = '+';
    int a = 2, b = 3, result = 0;
    switch (op) {
      case '+': result = a + b; break;
      case '-': result = a - b; break;
      case '*': result = a * b; break;
      case '/': result = (b != 0) ? a / b : 0; break;
      default:  printf("unknown op\n"); break;
    }
    printf("%d\n", result);
}

Common Pitfalls

• Missing break causes fall-through into the next case.
• Using non-integral types in switch expressions (not allowed in C).

Checks for Understanding

1. What does the default label do?