C++ program to Calculate Factorial of a Number Using Recursion

Example to find factorial of a non-negative integer (entered by the user) using recursion.

To understand this example, you should have the knowledge of following C++ programming topics:

This program takes a positive integer from user and calculates the factorial of that number. Suppose, user enters 6 then,

Factorial will be equal to 1*2*3*4*5*6 = 720

You'll learn to find the factorial of a number using a recursive function in this example.

Visit this page to learn, how you can use loops to calculate factorial.

Example: Calculate Factorial Using Recursion

#include<iostream>
using namespace std;

int factorial(int n);

int main()
{
    int n;

    cout << "Enter a positive integer: ";
    cin >> n;

    cout << "Factorial of " << n << " = " << factorial(n);

    return 0;
}

int factorial(int n)
{
    if(n > 1)
        return n * factorial(n - 1);
    else
        return 1;
}

Output

Enter an positive integer: 6
Factorial of 6 = 720

In the above program, suppose the user inputs a number 6. The number is passed to the factorial() function.

In this function, 6 is multiplied to the factorial of (6 - 1 = 5). For this, the number 5 is passed again to the factorial() function.

Likewise in the next iteration, 5 is multiplied to the factorial of (5 - 1 = 4). And, 4 is passed to the factorial() function.

This continues until the value reaches 1 and the function returns 1.

Now, each function returns the value back to compute 1 * 2 * 3 * 4 * 5 * 6 = 720, which is returned to the main() function.