Example: C Program to Check Armstrong Number using While loop

#include <stdio.h>

#include <math.h>

​

int main() {

    int x, y, z, rem, n = 0;

    float r = 0.0;

​

    // x - To store the input number

    // y & z - To store the storage of original input number to check

    // rem - To store the reminder

    // r - To store the result variable

​

    printf("-----Enter the integer number-----\n");

    scanf("%d", &x);

​

    z = y = x;

​

    while (y != 0) {

        y /= 10;

        ++n;

    }

​

    while (z != 0) {

        rem = z % 10;

        r += pow(rem, n);

        z /= 10;

    }

    // if x is equal to r, the number is an Armstrong number

    if ((int) r == x) {

        printf("%d is an Armstrong number.\n", x);

    } else {

        printf("%d is not an Armstrong number.\n", x);

    }

    return 0;

}