//non-recursive factorial program
//jleblanc 2.4.06
//PAC II
//Description: This program returns the factorial of an integer using each
//of the 3 iterative loop structures. for n! when n<1, function returns 1.

/*
1)  We spoke in class about "recursive" functions.
Examine the factorial program (sent separately).
Re-write the factorial function non-recursively, using
a loop instead.  Write it three times, once with each
C looping structure.
*/

#include <stdio.h>

int factorial_for(int n)
{
	int product=1;
	int x;

	for(x=1; x<=n; x++)
	{
		product=product*x;
	}
	return product;
}

int factorial_while(int n)
{
	int product=1;

	while ( n > 0)
	{
		product=product*n;
		n=n-1;
	}
		return product;
}

int factorial_dowhile(int n)
{
	int product=1;

	do
	{
		product=product*n;
		n=n-1;
	}
	while ( n > 0);
	
	if( product > 0)
		{return product;}
	else
		{return 1;}
}

void main()
{
	int input, answer;

 	printf(" Welcome to the factorial calculator \n");
 	printf(" Please enter the value: ");
	scanf("%d", &input); //Note if I enter say .5, the program pauses and then just quits
	
	answer=factorial_for(input);
	printf("\n Using a For loop, the factorial of %2d is %6d\n", input, answer); 
	answer=factorial_while(input);
	printf(" Using a While loop, the factorial of %2d is %6d\n", input, answer); 
	answer=factorial_dowhile(input);
	printf(" Using a Do While loop, the factorial of %2d is %6d\n", input, answer); 
}