Introduction to Functions

#include <iostream>

using namespace std;

int add(int a, int b) {
  int c;
  c = a + b;

  return c;
}

int main() {
  int num1 = 10, num2 = 15, sum;

  sum = add(num1, num2);

  cout << "Sum is " << sum;

  return 0;
}