Control Structures

This documentation covers the core control structures in C, including conditionals, loops, and the goto statement. These constructs control the flow of execution in a program.

Conditional Statements

if Statement

Executes a block of code only if the condition is true.

int x = 10;
if (x > 5) {
    printf("x is greater than 5\n");
}

if-else Statement

Adds an alternate block if the condition is false.

if (x > 5) {
    printf("x > 5\n");
} else {
    printf("x <= 5\n");
}

else-if Ladder

Checks multiple conditions in sequence.

if (x > 10) {
    printf("x > 10\n");
} else if (x == 10) {
    printf("x == 10\n");
} else {
    printf("x < 10\n");
}

switch Statement

Allows multiple execution paths based on the value of a variable.

int day = 3;
switch (day) {
    case 1:
        printf("Monday\n");
        break;
    case 2:
        printf("Tuesday\n");
        break;
    default:
        printf("Another day\n");
}

Loops

Loops execute a block of code repeatedly.

while Loop

Executes as long as the condition is true.

int i = 0;
while (i < 5) {
    printf("%d\n", i);
    i++;
}

do-while Loop

Executes the body at least once, then checks the condition.

int i = 0;
do {
    printf("%d\n", i);
    i++;
} while (i < 5);

for Loop

Compact loop syntax using initialization, condition, and increment.

for (int i = 0; i < 5; i++) {
    printf("%d\n", i);
}

Loop Control: break and continue

break Statement

Exits the loop immediately.

for (int i = 0; i < 10; i++) {
    if (i == 5) break;
    printf("%d\n", i);
}

continue Statement

Skips the current iteration and continues with the next.

for (int i = 0; i < 5; i++) {
    if (i == 2) continue;
    printf("%d\n", i);
}

goto Statement

The goto statement allows jumping to a labeled part of the program. It’s rarely used and can make code harder to follow, but it’s useful in certain low-level or cleanup scenarios.

Syntax

goto label;
// ... other code
label:
// code to jump to

Example

#include <stdio.h>

int main() {
    int x = 1;
    if (x == 1)
        goto skip;

    printf("This line is skipped\n");

skip:
    printf("Jumped to label\n");
    return 0;
}

Warning

Use goto sparingly. Overuse can make code difficult to read and debug. Prefer structured control flow (loops, functions) when possible.