Getting Started

Control Flow

Use if/else, switch, and loops to control program execution in C.

Conditional Statements

C provides if, else if, and else for conditional execution, plus the ternary operator.

Switch Statement

More efficient than long if/else chains when comparing one value against multiple integer or char constants.

Loops

  • for — known number of iterations
  • while — unknown iterations, check before
  • do-while — runs at least once, check after

Loop Control

  • break — exit the loop immediately
  • continue — skip to next iteration
  • goto — jump to a label (use sparingly)

Example

c
#include <stdio.h>

int main() {
    /* if / else */
    int score = 85;
    if (score >= 90) {
        printf("A\n");
    } else if (score >= 80) {
        printf("B\n");
    } else {
        printf("C or below\n");
    }

    /* Ternary operator */
    int max = (score > 80) ? score : 80;

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

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

    /* while loop */
    int n = 1;
    while (n <= 10) {
        printf("%d ", n);
        n++;
    }

    /* do-while */
    int num;
    do {
        printf("Enter positive number: ");
        scanf("%d", &num);
    } while (num <= 0);

    /* Nested loops with break */
    for (int i = 0; i < 3; i++) {
        for (int j = 0; j < 3; j++) {
            if (j == 2) break;  /* break inner loop */
            printf("(%d,%d) ", i, j);
        }
    }

    return 0;
}
Try it yourself — C