is there any problem in my code to identify armstrong number?

I am finding Armstrong number but it’s showing "not a Armstrong number" Everytime and I can’t find the solution. as my observation I think there is some problem the sum section. the sum is not giving the correct value.

#include<stdio.h>
#include<math.h>
int main()
{
    int num, original_num, sum=0, lastdigit, digit, count=1;

    printf("Enter the number: ");
    scanf("%d", &num);

    original_num = num;

    while (num >= 10)
    {
        count++;
        num /= 10;
    }
    digit = count;

    while (num > 0)
    {
        lastdigit = num % 10;
        sum += pow(lastdigit, digit);      /** here is the problem lying as my 
                                              observation, the sum is giving the 
                                              incorrect value.**/
        num/=10;
    }
    if (original_num == sum)
    {
        printf("The number is an ARMSTRONG number");
    }
    else
    {
        printf("The number is not a ARMSTRONG number");
    }
    return 0;
    }

>Solution :

num has already became single digit after first while loop(which counts the number of digits). In which case your second loop which takes every digit in the number and raise it to the n power is running only once.

You need to restore the number before second loop.

  num = original_num; 

   while (num > 0)
    {
        lastdigit = num % 10;
        sum += pow(lastdigit, digit);      
        num/=10;
    }