Program to find factorial of Number in C++

What is a Factorial of a number 'n'?

 The factorial of a number 'n' is the product of all number from 1 upto the number 'n' it is denoted by n!.  For example n=5 then factorial of 5 will be 1*2*3*4*5= 120. 5!= 120

Factorial program C++ Logic:

• First think what is the factorial of a number? How mathematically it can be calculated.
•  If you got this info then it will be very easier to make a C++ Program logic to find the factorial.
•  User enters a number and we have to multiply all numbers upto entered number.
• Like if user enters 6  then Factorial should be equal to factorial= 1*2*3*4*5*6.
• In this case a for Loop will be very helpful. It will start from one and multiply all numbers upto entered number after it loop will be terminated.
• Take a variable and initialized it to 1 and in loop store multiplication result into it like in below program a variable 
• Factorial is used for this purpose.what is we does not initialized it to 1 and initialized it to zero or remain it uninitialized. In case of 0 our result will be zero in case of any number entered
• In case of not initializing it our answer will correct mostly but if variable contains garbage value then we will not be able to get correct result. 
• It is recommended that to initialize it to one.

Source Code

#include<iostream>

using namespace std;

int main()

{

    int num,factorial=1;

    cout<<" Enter Number To Find Its Factorial:  ";

    cin>>num;

    for(int a=1;a<=num;a++)

    {

        factorial=factorial*a;

    }

cout<<"Factorial of Given Number is ="<<factorial<<endl;

    return 0;

}

Output