Sum of two numbers using a function

How to use functions in C++

Program to read two numbers from the keyboard and print the sum using a function

#include <iostream>
using namespace std;
 
int sum(int a, int b); //declare the function
 
int main() {
   int a = 0, b = 0;
   cout << "Enter a number ";
   cin >> a;
 
   cout << "Enter another number ";
   cin >> b;
 
   int c = sum(a, b); //call the sum function
 
   cout << "sum = " << c << endl;
 
   system("pause");
}   
 
int sum(int a, int b){
    return a + b;
}