C++ Program to Find Factorial

To Find Factorial of a positive integer n is equal factorial of a positive integer n is equal to 1*2*3*…n. You will learn to calculate the factorial of a number using for loop in this example.

To understand this example i.e C++ Program to Find Factorial, you should have the knowledge of following C++ programming topics:

• C++ for Loop

For any positive number n, it’s factorial is given by:

factorial = 1*2*3...*n

Factorial of a negative number cannot be found and factorial of 0 is 1.

In this program below, the user is asked to enter a positive integer. Then the factorial of that number is computed and displayed on the screen.

Find Factorial of a given number

#include <iostream>
using namespace std;

int main()
{
    unsigned int n;
    unsigned long long factorial = 1;

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

    for(int i = 1; i <=n; ++i)
    {
        factorial *= i;
    }

    cout << "Factorial of " << n << " = " << factorial;    
    return 0;
}

Output

Enter a positive integer: 12
Factorial of 12 = 479001600

Here variable factorial is of type unsigned long long.

It is because factorial of a number is always positive, that’s why unsigned the qualifier is added to it.

Since the factorial a number can be large, it is defined as long long.

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Ask your questions and clarify your doubts on how to find Factorial in C++ by commenting. Documentation.