/*
   testfunc11.cpp
   CIS 150
   6/9/2005
   David Klick
   
   Factorial functions.
*/

#include <iostream>
#include <iomanip>
using std::cout;
using std::setw;

int factn(int);  // non-recursive factorial function
int factr(int);  // recursive factorial function

int main(void) {
   int i;

   cout << "Non-recursive factorial calcs:\n";
   for (i=0; i<=10; i++) {
      cout << "The factorial of " << setw(2) << i
           << " is " << setw(7) << factn(i) << '\n';
   }
   
   cout << "\nRecursive factorial calcs:\n";
   for (i=0; i<=10; i++) {
      cout << "The factorial of " << setw(2) << i
           << " is " << setw(7) << factr(i) << '\n';
   }

   return 0;
}

/*
   Non-recursive factorial function
*/
int factn(int n) {
   int prod = 1;
   while (n > 0) prod *= n--;
   return prod;
}

/*
   Recursive factorial function
*/
int factr(int n) {
   if (n < 2) return 1;
   return n * factr(n-1);
}

/*
   Sample output:
   
   Non-recursive factorial calcs:
   The factorial of  0 is       1
   The factorial of  1 is       1
   The factorial of  2 is       2
   The factorial of  3 is       6
   The factorial of  4 is      24
   The factorial of  5 is     120
   The factorial of  6 is     720
   The factorial of  7 is    5040
   The factorial of  8 is   40320
   The factorial of  9 is  362880
   The factorial of 10 is 3628800

   Recursive factorial calcs:
   The factorial of  0 is       1
   The factorial of  1 is       1
   The factorial of  2 is       2
   The factorial of  3 is       6
   The factorial of  4 is      24
   The factorial of  5 is     120
   The factorial of  6 is     720
   The factorial of  7 is    5040
   The factorial of  8 is   40320
   The factorial of  9 is  362880
   The factorial of 10 is 3628800
*/