Loops and Control Flow Examples

Creates a number pattern using nested for loops.

#include <stdio.h>

int main() {
    int rows, i, j;
    
    printf("Enter number of rows: ");
    scanf("%d", &rows);
    
    printf("\nNumber Pattern:\n");
    for (i = 1; i <= rows; i++) {
        for (j = 1; j <= i; j++) {
            printf("%d ", j);
        }
        printf("\n");
    }
    
    return 0;
}

Calculates the sum of all digits in a number using while loop.

#include <stdio.h>

int main() {
    int num, sum = 0, digit;
    
    printf("Enter a number: ");
    scanf("%d", &num);
    
    while (num > 0) {
        digit = num % 10;
        sum += digit;
        num /= 10;
    }
    
    printf("Sum of digits: %d\n", sum);
    return 0;
}

Creates a menu system that runs until user chooses to exit.

#include <stdio.h>

int main() {
    int choice;
    
    do {
        printf("\nMenu:\n");
        printf("1. Option 1\n");
        printf("2. Option 2\n");
        printf("3. Option 3\n");
        printf("0. Exit\n");
        printf("Enter your choice: ");
        scanf("%d", &choice);
        
        switch(choice) {
            case 1:
                printf("You selected Option 1\n");
                break;
            case 2:
                printf("You selected Option 2\n");
                break;
            case 3:
                printf("You selected Option 3\n");
                break;
            case 0:
                printf("Exiting...\n");
                break;
            default:
                printf("Invalid choice!\n");
        }
    } while (choice != 0);
    
    return 0;
}

Generates multiplication tables using nested for loops.

#include <stdio.h>

int main() {
    int i, j, n;
    
    printf("Enter the number for multiplication table: ");
    scanf("%d", &n);
    
    printf("\nMultiplication table for %d:\n", n);
    for (i = 1; i <= 10; i++) {
        printf("%d x %d = %d\n", n, i, n * i);
    }
    
    printf("\nFull multiplication table:\n");
    for (i = 1; i <= 10; i++) {
        for (j = 1; j <= 10; j++) {
            printf("%4d", i * j);
        }
        printf("\n");
    }
    
    return 0;
}

Demonstrates the use of break statement in prime number checking.

#include <stdio.h>

int main() {
    int num, i;
    
    printf("Enter a number: ");
    scanf("%d", &num);
    
    if (num <= 1) {
        printf("%d is not a prime number.\n", num);
        return 0;
    }
    
    for (i = 2; i <= num / 2; i++) {
        if (num % i == 0) {
            printf("%d is not a prime number.\n", num);
            break;  // Exit loop early if factor found
        }
    }
    
    if (i > num / 2) {
        printf("%d is a prime number.\n", num);
    }
    
    return 0;
}

Uses continue statement to skip even numbers and print only odd numbers.

#include <stdio.h>

int main() {
    int i;
    
    printf("Odd numbers from 1 to 20:\n");
    for (i = 1; i <= 20; i++) {
        if (i % 2 == 0) {
            continue;  // Skip even numbers
        }
        printf("%d ", i);
    }
    printf("\n");
    
    return 0;
}

Creates a pyramid pattern using nested loops.

#include <stdio.h>

int main() {
    int rows, i, j, space;
    
    printf("Enter number of rows: ");
    scanf("%d", &rows);
    
    printf("\nPyramid Pattern:\n");
    for (i = 1; i <= rows; i++) {
        // Print spaces
        for (space = 1; space <= rows - i; space++) {
            printf(" ");
        }
        // Print stars
        for (j = 1; j <= 2 * i - 1; j++) {
            printf("*");
        }
        printf("\n");
    }
    
    return 0;
}

Finds the maximum element in an array using a for loop.

#include <stdio.h>

int main() {
    int arr[10], i, max, size;
    
    printf("Enter the number of elements (max 10): ");
    scanf("%d", &size);
    
    printf("Enter %d elements:\n", size);
    for (i = 0; i < size; i++) {
        scanf("%d", &arr[i]);
    }
    
    max = arr[0];  // Assume first element is maximum
    
    for (i = 1; i < size; i++) {
        if (arr[i] > max) {
            max = arr[i];
        }
    }
    
    printf("Maximum element: %d\n", max);
    return 0;
}