Loop Control Statements in C: break and continue

Loop control statements are essential for managing the flow of execution within loops in C programming. Two important statements are break and continue. They provide fine-grained control over how loops iterate.

Understanding break and continue

break Statement

The break statement is used to immediately terminate the execution of a loop (for, while, or do-while). When the break statement is encountered inside a loop, the control is transferred to the statement immediately following the loop.

continue Statement

The continue statement is used to skip the rest of the current iteration of a loop and move to the next iteration. When the continue statement is encountered inside a loop, the remaining statements within the loop's body for that iteration are skipped, and the loop proceeds to the next iteration (if the loop condition allows).

Examples in for, while, and do-while Loops

for Loop with break

 #include <stdio.h>

int main() {
    for (int i = 1; i <= 10; i++) {
        if (i == 5) {
            break; // Exit the loop when i is 5
        }
        printf("Value of i: %d\n", i);
    }
    printf("Loop terminated.\n");
    return 0;
} 

In this example, the loop prints the values of i from 1 to 4. When i becomes 5, the break statement is executed, and the loop is terminated. The output will be:

 Value of i: 1
Value of i: 2
Value of i: 3
Value of i: 4
Loop terminated. 

for Loop with continue

 #include <stdio.h>

int main() {
    for (int i = 1; i <= 10; i++) {
        if (i % 2 == 0) {
            continue; // Skip even numbers
        }
        printf("Value of i (odd): %d\n", i);
    }
    printf("Loop finished.\n");
    return 0;
} 

In this example, the loop prints only the odd numbers from 1 to 10. When i is even, the continue statement is executed, skipping the printf statement for that iteration. The output will be:

 Value of i (odd): 1
Value of i (odd): 3
Value of i (odd): 5
Value of i (odd): 7
Value of i (odd): 9
Loop finished. 

while Loop with break

 #include <stdio.h>

int main() {
    int i = 1;
    while (i <= 10) {
        if (i == 7) {
            break; // Exit the loop when i is 7
        }
        printf("Value of i: %d\n", i);
        i++;
    }
    printf("Loop terminated.\n");
    return 0;
} 

This while loop prints the values of i from 1 to 6. When i becomes 7, the break statement is executed, and the loop is terminated. The output will be:

 Value of i: 1
Value of i: 2
Value of i: 3
Value of i: 4
Value of i: 5
Value of i: 6
Loop terminated. 

while Loop with continue

 #include <stdio.h>

int main() {
    int i = 0;
    while (i < 10) {
        i++;
        if (i % 3 != 0) {
            continue; // Skip numbers not divisible by 3
        }
        printf("Value of i (divisible by 3): %d\n", i);
    }
    printf("Loop finished.\n");
    return 0;
} 

This while loop prints the numbers from 1 to 10 that are divisible by 3. When i is not divisible by 3, the continue statement is executed, skipping the printf statement for that iteration. The output will be:

 Value of i (divisible by 3): 3
Value of i (divisible by 3): 6
Value of i (divisible by 3): 9
Loop finished. 

do-while Loop with break

 #include <stdio.h>

int main() {
    int i = 1;
    do {
        if (i == 4) {
            break; // Exit the loop when i is 4
        }
        printf("Value of i: %d\n", i);
        i++;
    } while (i <= 5);
    printf("Loop terminated.\n");
    return 0;
} 

This do-while loop prints the values of i from 1 to 3. When i becomes 4, the break statement is executed, and the loop is terminated. The output will be:

 Value of i: 1
Value of i: 2
Value of i: 3
Loop terminated. 

do-while Loop with continue

 #include <stdio.h>

int main() {
    int i = 0;
    do {
        i++;
        if (i % 5 != 0) {
            continue; // Skip numbers not divisible by 5
        }
        printf("Value of i (divisible by 5): %d\n", i);
    } while (i <= 10);
    printf("Loop finished.\n");
    return 0;
} 

This do-while loop prints the numbers from 1 to 10 that are divisible by 5. When i is not divisible by 5, the continue statement is executed, skipping the printf statement for that iteration. The output will be:

 Value of i (divisible by 5): 5
Value of i (divisible by 5): 10
Loop finished. 

Important Considerations

• Using break and continue can sometimes make code harder to read and understand. Consider whether alternative loop structures or conditional statements could achieve the same result with greater clarity.
• Carefully plan the logic of your loops when using break and continue to avoid unintended behavior.