Using - C
  
 Source Code
  

    
      #include<stdio.h>
      #include<math.h>

      int sumOfCube(int num);

      void main() {
        int num;
        printf("Enter a number:  ");
        scanf("%d",&num);
        
        if(num == sumOfCube(num))
          printf("It is a Armstrong Number!");
        else
          printf("It is not a Armstrong Number!");
      }
      
      int sumOfCube(int num) {
      int sum=0, cubeOfdigit, digit;
          while(num!=0) {
          digit = num % 10;
          cubeOfdigit = pow(digit,3);
          sum += cubeOfdigit;
          num /= 10;
          }
      return sum;
      }
      
    

Case-1
----------------------------------------
Enter a number:  153
It is a Armstrong Number!


Case-2 
----------------------------------------
Enter a number:  123
It is not a Armstrong Number!

        
Using - C++
        
 Source Code
        

        
          #include<iostream>
#include<math.h>
using namespace std;

int sumOfCube(int n);

int main() {
int n, sum=0;
	cout<<"Enter a number: ";
	cin>> n;
	
	if(n == sumOfCube(n))
		cout<< "It is a Armstrong Number!";
	else 
		cout<< "It is not a Armstrong Number!";
		
	return 0;
}

int sumOfCube(int n) {
int sum=0, cubeOfdigit, digit;
    while(n!=0) {
    digit = n % 10;
    cubeOfdigit = pow(digit,3);
    sum += cubeOfdigit;
    n /= 10;
    }
return sum;
}

      

Case-1
----------------------------------------
Enter a number:  407
It is a Armstrong Number!


Case-2 
----------------------------------------
Enter a number:  315
It is not a Armstrong Number!