C++ program to find factorial of a number

Here are C++ programs to find factorial of a number using simple while-loop, functions, recursion, tail recursion, class and also a program to calculate factorial of first N numbers
Factorial of n is denoted by n! and it is calculated by the product of integer numbers from n to 1.
For example 3! = 3*2*1=6. Similarly n!=n*(n-1)........*2*1.

C++ program to find factorial of number

#include<iostream>
using namespace std;
int main()
{
    int number,fact=1,num2;
    cout<<"Enter number ";
    cin>>number;
    num2=number;
    while(number!=0)
    {
        fact*=number;
        number--;
    }
    cout<<"Factorial of "<<num2<<" = "<<fact;
    return 0;
}

C++ program to find factorial of number using function

#include<iostream>
using namespace std;
int fact(int num)
{
    for(int i=num-1;i>1;i--)
        num*=i;
    return num;
}
int main()
{
    int number,num2;
    cout<<"Enter number ";
    cin>>number;
    num2=fact(number);
    cout<<"Factorial of "<<number<<" = "<<num2;
    return 0;
}

C++ program to find factorial of number using recursion

#include<iostream>
using namespace std;
int fact(int num)
{
    if(num==1)
        return 1;
    return num*fact(num-1);
}
int main()
{
    int number,num2;
    cout<<"Enter number ";
    cin>>number;
    num2=fact(number);
    cout<<"Factorial of "<<number<<" = "<<num2;
    return 0;
}

C++ program to find factorial of number using tail recursion

#include<iostream>
using namespace std;
int fact(int num,int n)
{
    if(n==1)
        return num;
    return fact(num*n,n-1);
}
int main()
{
    int number,num2;
    cout<<"Enter number ";
    cin>>number;
    num2=fact(number,number-1);
    cout<<"Factorial of "<<number<<" = "<<num2;
    return 0;
}

C++ program to find factorial of number using class

#include<iostream>
using namespace std;
class calfact
{
private:
    int number;
public:
    void getnum(int i)
    {
        number=i;
    }
    int fact();
};
int calfact::fact()
{
    for(int i=number-1;i>1;i--)
         number*=i;
    return number;
}
int main()
{
    int number,num2;
    calfact factorial;
    cout<<"Enter number ";
    cin>>number;
    factorial.getnum(number);
    num2=factorial.fact();
    cout<<"Factorial of "<<number<<" = "<<num2;
    return 0;
}

C++ program to calculate factorial of first N numbers

#include<iostream>
#include<math.h>
using namespace std;
int main()
{
    long double fact=1,y;
    int n;
    cout<<"Enter the value of n ";
    cin>>n;
    for(int i=1;i<=n;i++)
    {
       y=i;
       while(y>0)
       {
           fact*=y;
           y--;
       }
       cout<<fact<<" ";
       fact=1;
    }
    return 0;
}

OUTPUT