Control Flow: Iteration (for, while, do-while, break, continue)

1Concept

C provides 3 loop constructs: 1. for (init; condition; step): Standard counted loop. 2. while (condition): Evaluates condition before each iteration. 3. do { ... } while (condition): Guarantees body executes at least once. break exits the loop immediately; continue skips directly to the next iteration step.

2Architecture Diagram

for (i=0; i<N; i++):
[Init i=0] --> [i < N ?] --YES--> [Body] --> [i++] --^
                    |
                   NO
                    v
               [Exit Loop]

3Code Example

#include <stdio.h>

int main(void) {
    printf("=== Counted For Loop with Continue ===\n");
    for (int i = 1; i <= 6; i++) {
        if (i == 4) {
            printf("Skipping %d (continue)\n", i);
            continue;
        }
        printf("Step %d\n", i);
    }

    printf("\n=== Do-While Minimum Single Execution ===\n");
    int count = 10;
    do {
        printf("Do-While ran with count = %d (even though count > 5)\n", count);
        count++;
    } while (count < 5);

    return 0;
}

4Expected Output

=== Counted For Loop with Continue ===
Step 1
Step 2
Step 3
Skipping 4 (continue)
Step 5
Step 6

=== Do-While Minimum Single Execution ===
Do-While ran with count = 10 (even though count > 5)

5Key Takeaways

• ✓do-while loops test condition at the bottom, guaranteeing 1 execution.
• ✓continue skips remaining statements and jumps to the update step in for loops.
• ✓Always ensure loop termination conditions prevent infinite loops.