Loops in C (for, while, do-while)

Master loops in C programming: for loops, while loops, and do-while loops. Learn iteration mechanics, break and continue statements, and avoiding infinite loops.

Loops enable repetitive execution of code blocks based on boolean conditions. C provides three primary loop constructs: for loops, while loops, and do-while loops.

A for loop is ideal for counting and index-based iterations where initialization, condition, and increment expressions are bundled in a single line. A while loop tests its condition before executing the loop body, making it ideal for event loops and input reading.

A do-while loop is unique because it guarantees that the loop body executes at least once before the condition is evaluated at the bottom.

Interactive Runnable C Implementation

#include <stdio.h>

int main(void) {
    printf("=== 1. For Loop with Break & Continue ===\n");
    for (int i = 1; i <= 8; i++) {
        if (i == 3) {
            printf("  Skipping iteration i = %d (continue)\n", i);
            continue;
        }
        if (i == 7) {
            printf("  Terminating early at i = %d (break)\n", i);
            break;
        }
        printf("  For index: %d\n", i);
    }

    printf("\n=== 2. While Loop (Bitwise Power Generator) ===\n");
    int power = 1;
    while (power <= 32) {
        printf("  2^k value = %d\n", power);
        power *= 2;
    }

    printf("\n=== 3. Do-While Loop (Guaranteed 1+ Run) ===\n");
    int count = 0;
    do {
        printf("  Executed do-while body (count = %d)\n", count);
        count++;
    } while (count < 2);

    return 0;
}

Open example in compiler

Expected Output

=== 1. For Loop with Break & Continue ===
  For index: 1
  For index: 2
  Skipping iteration i = 3 (continue)
  For index: 4
  For index: 5
  For index: 6
  Terminating early at i = 7 (break)

=== 2. While Loop (Bitwise Power Generator) ===
  2^k value = 1
  2^k value = 2
  2^k value = 4
  2^k value = 8
  2^k value = 16
  2^k value = 32

=== 3. Do-While Loop (Guaranteed 1+ Run) ===
  Executed do-while body (count = 0)
  Executed do-while body (count = 1)