C++ Program To Find Factorial Of A Number N

Factorial Of Number N

As you may know that the factorial of a positive number is the product of all the integer numbers from 1 up to that particular number say n.

For Example, the factorial of the number 4 can be defined as 4! that is equal to 1*2*3*4 = 24.

Factorial can only be defined for positive integers.

We can only find the factorial of positive numbers, therefore the factorial of a negative number doesn’t exist, and the factorial of 0 is 1.

Example: Factorial of Number 4

The factorial of the positive number 4 is 24 as you can see below.

   4! = 1 * 2 * 3 * 4 = 24  Ans.

Factorial of a number n C++ Program

// factorial of a number c++ program
//techindetail.com

#include <iostream>
using namespace std;

int main(){
    int n;   //to store the user value
    
//long double bcz the value may be bigger
    long double factorial = 1.0;

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

    if (n < 0)
        cout << "Error! Factorial of a negative number doesn't exist.";
    else {
        for(int i = 1; i <= n; ++i) {
            factorial = factorial * i;
        }
        cout << "Factorial of " << n << " = " << factorial;    
    }

    return 0;
}Code language: PHP (php)

Output Of Above C++ Program

Enter a positive integer: 4
Factorial of 4 = 24

Enter a positive integer: 5
Factorial of 5 = 120

C++ Program to find the factorial using Recursion

//  factorial using recursion  
//  techindetail.com

#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;
}
Code language: PHP (php)

Output Of Above C++ Program

Enter an positive integer: 5
Factorial of 5 = 120