# C++ program to find factorial of a number

Given an integer number, we have to find the factorial of the given number using C++ program.
[Last updated : February 28, 2023]

## Finding the factorial of a number in C++

In this program, we will learn how to find factorial of a given number using C++ program? Here, we will implement this program with and without using user define function.

## Logic to find the factorial of a number

1. Input a number
2. Initialize the factorial variable with 1
3. Initialize the loop counter with N (Run loop from number (N) to 1)
4. Multiply the loop counter's value with factorial variable

## Program to find factorial using loop in C++

```#include <iostream>
using namespace std;

int main()
{
int num, i;
long int fact = 1;

cout << "Enter an integer number: ";
cin >> num;

for (i = num; i >= 1; i--)
fact = fact * i;

cout << "Factorial of " << num << " is = " << fact << endl;

return 0;
}
```

Output

```Enter an integer number: 6
Factorial of 6 is = 720
```

## Program to find factorial using User Define Function in C++

```#include <iostream>
using namespace std;

//function declaration
long int factorial(int n);

int main()
{
int num;

cout << "Enter an integer number: ";
cin >> num;

cout << "Factorial of " << num << " is = " << factorial(num) << endl;

return 0;
}

//function defintion
long int factorial(int n)
{
int i, fact = 1;

for (i = n; i >= 1; i--)
fact = fact * i;

return fact;
}
```

Output:

```Enter an integer number: 6
Factorial of 6 is = 720
```