check Armstrong number in the C program

#include<stdio.h>
#include<math.h>
#define pow
int main()
{
    int num,num1,num2,n,q,sum=0,no_of_digits=0;
    printf("enter  a number\n");
    scanf("%d",&num);
    num1=num2=num; //storing the entered number in another variable 'num1'
    while (num!=0) //calclating and storing the number of digits in 'digit'
    {
        num=num/10; //dividing the number by 10. int data type ignores the decimal value, giving an integer
        no_of_digits++; 
    }
    while (num1!=0) 
    {
        n=num1%10; //taking one digit at a time in n
        q=pow(n,no_of_digits);//each digit^no. of digits
        sum=sum+q; // sum of all digit^no. of digits
        num1=num1/10;
        
    }
     printf("Sum of each digit^no. of digits =%d\n",sum);
     if (sum==num2)
        printf("%d is an armstrong number\n",num2);
     else
        printf("%d is NOT an armstrong number\n",num2);

  return 0;
} 

MY result: Sum of each digit^no. of digits =9 370 isn't an armstrong number 

Likewise, if i don't add the #define pow line,i get the following error. /usr/bin/ld: /tmp/ccGBiCYH.o: in function main': 7.c:(.text+0xda): undefined reference to pow' collect2: error: ld returned 1 exit status. 

Before trying this code I Read several Articles on the web on Armstrong number in C to understand the concept in a better way, Here, is the article I've read from Wikipedia, Scaler and Quora.