Lab: while Loop

Program 1: Print Numbers from 1 to N

Objective: Input a number N and print all numbers from 1 to N.

#include <stdio.h>

void main() {
    int i = 1, N;
    
    printf("Enter a number: ");
    scanf("%d", &N);
    
    while (i <= N) {
        printf("%d ", i);
        i++;
    }
}

Program 2: Sum of Digits of a Number

Objective: Calculate the sum of digits of a given number.

#include <stdio.h>

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

Program 3: Check if a Number is Prime

Objective: Input a number and check whether it is a prime number.

#include <stdio.h>

void main() {
    int num, i = 2, flag = 1;
    
    printf("Enter a number: ");
    scanf("%d", &num);
    
    if (num <= 1) {
        flag = 0;  // Numbers less than or equal to 1 are not prime
    }
    
    while (i <= num / 2) {
        if (num % i == 0) {
            flag = 0;
            break;
        }
        i++;
    }
    
    if (flag == 1) {
        printf("%d is a prime number\n", num);
    } else {
        printf("%d is not a prime number\n", num);
    }
    
}

Program 4: Find the Greatest Common Divisor (GCD)

Objective: Calculate the GCD of two numbers using a while loop.

#include <stdio.h>

void main() {
    int a, b;
    
    printf("Enter two numbers: ");
    scanf("%d %d", &a, &b);
    
    while (a != b) {
        if (a > b)
            a = a - b;
        else
            b = b - a;
    }
    
    printf("GCD = %d\n", a);
}

5. Multiplication table using while loop

#include <stdio.h>

void main() {
    int num, i = 1;

    // Input from the user
    printf("Enter a number to generate its multiplication table: ");
    scanf("%d", &num);

    // While loop for multiplication table
    while (i <= 10) {
        printf("%d x %d = %d\n", num, i, num * i);
        i++;  // Increment the counter
    }

}

Output:

Enter a number to generate its multiplication table: 5
5 x 1 = 5
5 x 2 = 10
5 x 3 = 15
5 x 4 = 20
5 x 5 = 25
5 x 6 = 30
5 x 7 = 35
5 x 8 = 40
5 x 9 = 45
5 x 10 = 50