Calculating factorial using functions

In my previous blogs, I have calculated factorial of a given number using while,do-while and for loop.Today I will calculate factorial using function.


Below is the source code of this program.

Source code

#include<iostream>
#include<conio.h>
using namespace std;
void factorial(int n);
main()
{
int n;
cout<<"Enter any number:";
cin>>n;
factorial(n);//function call

getch();

}
void factorial(int n)
{

int c,f=1;
for( c=1;c<=n;c++)
{
f=f*c;
}
cout<<"Factorial="<<f;

}

Output

Explanation:

Line #4:

             It is function declaration with a parameter and no argument.

Line #10:

                It is the function call with a parameter.

Line #13:

                It is the function definition which tells what a function actually does.It is also without argument and with a parameter.

Logic of factorial

.For your revision,I will explain what a factorial actually is.

The factorial of 4 can be calculated as

4!=4*3*2*1=24

In the same way,factorial of 5 can be calculated as

5!=5*4
   =20
   =20*3
   =60
   =60*2
   =120
   =120*1
   =120