C++ Program to Find Factorial

In this article, you’ll learn about how to make C++ Program to Find Factorial.

The factorial of a negative number doesn’t exist. And the factorial of 0 is 1.

Program to find the factorial of a given number using for loop

#include <iostream>
using namespace std;

int main() {
    int n;
    long 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 *= i;
        }
        cout << "Factorial of " << n << " = " << factorial;    
    }

    return 0;
}

Output

Enter a positive integer: 4
Factorial of 4 = 24

In the above program, we take a positive integer from the user and compute the factorial using for loop. We print an error message if the user enters a negative number.

Program to find the factorial of a given number using recursion

#include <iostream>
using namespace std;

int fact(int n){
    if(n>0)
    {
        return n*fact(n-1);
    }
    else 
    return 1;
}
int main() {
    int num;
    cin>>"Enter an integer to compute the factorial "
    cout<<fact(num);
    return 0;
}

A factorial is represented by a number and a  ” ! ”  mark at the end. It is widely used in permutations and combinations to calculate the total possible outcomes. A French mathematician Christian Kramp firstly used the exclamation.