GCD problem

[Seeshi]

I really don't need help with the gcd formula. I have that down, but I keep getting strange errors that I don't know how to fix. Here is my code.

#include <iostream>
#include <iomanip>
#include <cstdio>
using namespace std;

int greatestCommonDivisor( int a, int b )
{
	int c;
	a = abs(a);
	b = abs(b);

	if (b = 0)
		return a;
	else
		while (b > 0)
		{
			c = b;
			b = a % b;
			a = c;
		}
		return c;
}

int main ()
{
	int x;
	int y;
	int gcd;

	cout << "Please enter the first number" << endl;
	cin >> x;
	cout << "Please enter the second number" << endl;
	cin >> y;

	while ( x < y );
	do
	{
		cout << "Invalid entry, x is smaller than y. Please enter first number." << endl;
		cin >> x;
		cout << "Please enter a number smaller than the first number for the second number." << endl;
		cin >> y;
	}

	gcd = greatestCommonDivisor( x, y );

	cout << "The greatest common divisor is" << gcd << endl;

	getchar();

	return 0;
};

At line 44 I am getting this error "syntax error: identifier 'gcd'"
Also, I am getting an error saying I am trying to use "int c" without initializing it. I can't figure out what went wrong!

[hanst99]

Also, I am getting an error saying I am trying to use "int c" without initializing it.

Exactly what it says on the tin. You are using "c" without assigning a value to it first.

The syntax error is because you do this

while ( x < y );
	do
	{
		cout << "Invalid entry, x is smaller than y. Please enter first number." << endl;
		cin >> x;
		cout << "Please enter a number smaller than the first number for the second number." << endl;
		cin >> y;
	}

When it should be this:

while ( x < y )
	{
		cout << "Invalid entry, x is smaller than y. Please enter first number." << endl;
		cin >> x;
		cout << "Please enter a number smaller than the first number for the second number." << endl;
		cin >> y;
	}

The syntax error occurs at gcd because "while" is expected there (for a do-while loop).

Also please look at the first if in your gcd function. I don't think you want it to do what it does.

[Seeshi]

Ok I fixed the two errors, but I don't really know what you mean about the if. Also my output stops after I enter the value for y and I cant determine why...

[hanst99]

if (b = 0) //b is set to 0. This is never true because the value of this expression is 0. == is check for equality.
		return a;
	else
		while (b > 0) //since b is always 0 here, the loop is never entered
		{
			c = b;
			b = a % b;
			a = c;
		}
		return c; /*unitialized value for c is returned.
                                Or maybe initialized if you assigned a value to c now. 
                                Anyways it's not what you want*/

[Seeshi]

Ah! Thank you! I totally forgot about the whole = and == thing. I feel so silly...