# C++ program to find factorial of a number

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:

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;
}
```