Quick C++ function tutorial

In order to use a c++ function, we need these three steps…

1) Declare the function at the top of the c++ file before it appears in any other functions that call it.

int sum(int first, int second);

2) Write the function it selves within the c++ file.

int sum(int number1, int number2) {
    return (number1 + number2);
}

3) Use it!

cout << "The total is " << sum(number1, number2) << endl; 

Below program will call the sum function and outputs the total of the two numbers.

#include <iostream>

using namespace std;
int sum(int first, int second);

int main()
{
    int number1, number2;
    cout << "enter two number : " << endl; 
    cin >> number1;
    cin >> number2;
    cout << "The total is " << sum(number1, number2) << endl; 
    return 0;
}

int sum(int number1, int number2) {
    return (number1 + number2);
}
sum up two number
sum up two numbers

Below is another program where the function will repeatedly calling it selves to produce a factorial of a number.

#include <iostream>

using namespace std;
int factorial(int number);

int main()
{
    int number;
    cout << "enter a number : " << endl; 
    cin >> number;
    cout << "The factorial of that number is " << factorial(number) << endl; 
    return 0;
}

int factorial(int number) {
    if (number <= 1) {
        return 1;
    } else {
        return number * factorial(number - 1); 
    }
}
The function calls is putting under the memory stack
The function calls is putting under the memory stack

This tutorial is a simple one but that is basically what you need to create a function which can operate by it’s own!

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