C++ Program to Find Factorial of a Number Using Recursion

In this post, you will learn how to Find Factorial of a Number Using Recursion in C++ programming language.

This lesson will teach you how to Find Factorial of a Number Using Recursion, with a recursion statement, mathematical operations and decision making statement using the C++ Language. Let’s look at the below source code.

How to Find Factorial of a Number Using Recursion?

Source Code

#include<iostream>
using namespace std;
int factorial(int n)
{
    if(n > 1)
        return n * factorial(n - 1);
    else
        return 1;
}
int main()
{
    int n;
    cin >> n;
    cout << "Enter a positive integer: "<<n<<endl;
    cout << "\nFactorial of the number " << n << " is: " << factorial(n);
    return 0;
}

Input

6

Output

Enter a positive integer: 3
Factorial of the number 3 is: 6

The statements #include<iostream>, using namespace std, int main are the main factors that support the function of the source code. Now we can look into the working and layout of the code’s function.

1. When function is called within the same function, it is known as recursion. In this program we find out the sum of the first n numbers, using recursion.
2. In this code we have two sections, in the first one we declare the function int factorial(int n) to initiate the recursive function, where we declare the variable n as an integer.
3. Using the decision making statements assign the condition to verify if the value of n is greater than 1. If the condition is satisfied then the return n * factorial(n - 1) is executed. If not the execution moves to the else statement which returns the value 1.
4. Here the value of factorial holds the number for which we have to find the factorial. The execution starts by default with 1 (n). The value is verified with the if condition, when the condition is true the value  is used in the mathematical function return n * factorial(n - 1)  or else it returns the value 1.
5. The function is repeated with the recursion function till the condition is not true.
6. The function then moves to the output section of the code, where we use output statements to display the answer stored in factorial(n).

Note: The ‘ << endl ‘ in the code is used to end the current line and move to the next line and ‘\n’ is also a new line function, to understand how both the functions work exclude it from the code, move it around and work with it.