I created this function and I need help turning this into a recursive function

#include "stdafx.h"
#include "stdio.h"

int fact (int n); // function prototype//

int main (void)
{
	int n,result;

	printf("please enter a positive integer");
	scanf("%d", &n);

	result = fact(n);

	printf("The answer is %d\n", result);

	return 0;
}

int fact(int n)
{
	int i, product=1;
		
	for(i=1; i<=n; i++) //algorithm
	{
		product *= i;
	}

	return (product);
}

Thanks for the guidance

Perhaps you should make an effort to search on the form. There might be like tons of results on this issues. But here is the pesudo code.

<return type of int> function name FACT ( taking int as an argument )
{
   if n equals to zero
      return one;
   else
       return n multiple FACT ( n minus one );
}

NB: Learn to start using code tags!

ssharish

Is this correct for a recursive function I still have the following error (23) : error C2447: '{' : missing function header (old-style formal list?)

#include "stdafx.h"
#include "stdio.h"

int fact (int n); // function prototype//

int main (void)
{
	int n,result;

	printf("please enter a positive integer");
	scanf("%d", &n);
	result = fact(n);
	printf("The answer is %d\n", result);
	return 0;
}
	
   int return1 (int n);
   {
	   if (n<=1)
		   return1;
	   else
		   return(n*fact(n-1));
	}
int return1 (int n);

Why is that semicolon there??? Delete that! Syntax error

ssharish

When deleting the semicolon the following errors shows up error LNK2019: unresolved external symbol "int __cdecl fact(int)" (?fact@@YAHH@Z) referenced in function _main
C:\Documents and Settings\Owner\My Documents\Visual Studio 2008\Projects\lab 8.1\Debug\lab 8.1.exe : fatal error LNK1120: 1 unresolved externals

int return1 (int n);

Why is that semicolon there??? Delete that! Syntax error

ssharish

And why is it called return1??? It should be fact!!!

Well there are few thing which you need to consider. First of all the function name is not write. In you code you have declared a function prototype clearly, but why dosn;t that reflect in your function definiation.

Your function name is return1 which should be return1. And then within the function your should check for n <= 0 not 1 or n == 0 . And also if thats true you should return 1 not return1 . Give a space between return and 1.

ssharish

Here it is...

#include "stdio.h"
#include "conio.h"
int fact (int n); // function prototype//

int main (void)
{
	int n,result;

	printf("please enter a positive integer");
	scanf("%d", &n);

	result = fact(n);

	printf("The answer is %d\n", result);

	getch();
	return 0;
}

int fact (int n)
{
	   if (n<=1)
		   return 1;
	   else
		   return(n*fact(n-1));
}
Comments
Point the mistake the OP did rather. Dont do his work!

how could I add something to the function so it calculates when and if n is negative

how could I add something to the function so it calculates when and if n is negative

Well, you got to be pretty careful on what your placing in the recursive function. The function is built to find the factorial for a given number. Tell me what are you trying to achieve.

Why do you want to check for n is negative??

if( n < 0 ) {   ...   }

This should check for the negative function. You could perhaps replace the statment in your fact function and see what output you get. I would guess not the right answer your looking for!

ssharish

Isn't negative factorial kind of wrong altogether?

YES it is :) Perhaps the OP should check the value of n, before sending the value to the fact function.

print "Value for n ?"
   read n

if( n >= 1 )
   print fact( n )
else
  Error

ssharish

how could I add something to the function so it calculates when and if n is negative

Yeah, negative factorial is wrong, why do you want that anyways?...

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