Lab: do-while Loop

Program 1: Display Menu Until User Enters 0

Objective: Show a menu, take input from the user, and continue until the user enters 0.

#include <stdio.h>

int main() {
  int choice;
  
  do {
    printf("Menu:\n");
    printf("1. Option 1\n");
    printf("2. Option 2\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 0:
        printf("Exiting...\n");
        break;
      default:
        printf("Invalid choice!\n");
    }
  } while (choice != 0);
  
  return 0;
}

Program 2: Reverse a Number

Objective: Reverse the digits of a number using a do-while loop.

#include <stdio.h>

int main() {
  int num, reverse = 0, remainder;
  
  printf("Enter a number: ");
  scanf("%d", &num);
  
  do {
    remainder = num % 10;
    reverse = reverse * 10 + remainder;
    num /= 10;
  } while (num != 0);
  
  printf("Reversed number = %d\n", reverse);
  
  return 0;
}

Program 3: Sum of Even Numbers between 1 and N

Objective: Input a number N and calculate the sum of all even numbers between 1 and N.

#include <stdio.h>

int main() {
  int i = 2, N, sum = 0;
  
  printf("Enter a number: ");
  scanf("%d", &N);
  
  do {
    sum += i;
    i += 2;
  } while (i <= N);
  
  printf("Sum of even numbers between 1 and %d = %d\n", N, sum);
  
  return 0;
}

Program 4: Find Armstrong Number

Objective: Check whether a given number is an Armstrong number.

#include <stdio.h>

int main() {
  int num, originalNum, remainder, result = 0;
  
  printf("Enter a three-digit number: ");
  scanf("%d", &num);
  
  originalNum = num;
  
  do {
    remainder = num % 10;
    result += remainder * remainder * remainder;
    num /= 10;
  } while (num != 0);
  
  if (result == originalNum) {
    printf("%d is an Armstrong number.\n", originalNum);
  } else {
    printf("%d is not an Armstrong number.\n", originalNum);
  }
  
  return 0;
}