# C++ Program to find the Factorial of a Number

## Program to find the Factorial of a Number

Here we will discuss how to find the factorial of a number entered by the user in C++ programming language.

Factorial of any number is the product of it and all the positive numbers below it for example factorial of 5 is 120

5!=5 x 4 x 3 x 2 x 1

=120

To find the factorial of a number we will use a for loop.

### Working

Let’s see how the code works

• User gives an input
• Input is stored in an int type variable say num.
• num is checked for being a negative number if true then input is invalid.
• Otherwise a for loop is started
• The loop starts with i=num
• In every loop cycle i is multiplied by fact and its value is decremented by 1.
• Loop works until i is greater than 0.
• fact is printed as it is the factorial of the given number. ### C++ Code

`//C++ Program//Factorial of a number#include<iostream>using namespace std;//main programint main(){    //initializing variables    int fact=1,num;    cout<<"Enter the number: ";    //user input    cin>>num;    //checking for negative input    if(num<0)        cout<<"Invalid input!!\nEnter whole numbers only";    // for positive numbers    else    {        for(int i=num;i>0;i--)        {            fact*=i;        }        cout<<"Factorial of "<<num<<" is "<<fact;    }    return 0;}`

#### Output

`Enter the number: 8Factorial of 8 is 40320`