Write a Program in C++ That Do Recursive Function Factorial

// Recursive function factorial.

#include <iostream>

#include <iomanip>

using namespace std;

unsigned long factorial( unsigned long ); // function prototype

int main()

{

   // calculate the factorials of 0 through 10

   for ( unsigned int counter = 0; counter <= 10; ++counter )

      cout << setw( 2 ) << counter << "! = " << factorial( counter ) 

         << endl;

} // end main

// recursive definition of function factorial

unsigned long factorial( unsigned long number )

{

   if ( number <= 1 ) // test for base case

      return 1; // base cases: 0! = 1 and 1! = 1

   else // recursion step

      return number * factorial( number - 1 );

} // end function factorial