What is going on here?

[Ben Duncan]

I was set a challenge, and I thought that I had done well, but it appears not.
The challenge was this:
"Write a program that repeatedly asks the user to input a pair of numbers until at least one of the pair is 0.
The function should return the answer to main(), which should report the result.
(The harmonic mean = 2.0 * x * y / (x + y))"



The problem with my simple code is that nothing returns from the function. and when the user types a 0, an infinite loop occurs.

#include "stdafx.h"
#include <iostream>
#include <cctype>
using std::cout;
using std::cin;

double harmonicmean(unsigned int x, unsigned int y);

int main()
{
	unsigned int x,y;
	cout << "Please enter two positive integers\n";

	cin >> x >> y;

	while(x!= 0 || y!= 0)
	{
		if(isalpha(x) || isalpha(y))
			break;

		harmonicmean(x,y);
		cout << "Enter another two numbers, or zero to stop\n";
		cin.clear();
		cin >> x >> y;
	
	}



	char faefasdfsdg;
	cin >> faefasdfsdg;
	return 0;
}

double harmonicmean(unsigned int x, unsigned int y)
{
	double total = (2.0 * x * y) / (x + y);
	
	return total;
}

Can anyone give me any hints as to what I've done wrong?

[Moschops]

The function does return the value. The problem is that you're not doing anything with it.

Try

double returnedValue = harmonicmean(x,y);
cout << returnedValue;

As for stopping, look at this:

while(x!= 0 || y!= 0)

Let's say that I enter x as zero, and y as some other number. Will the loop stop? No. The loop will keep going as long as x isn't zero OR y isn't zero. The only way to stop the loop is to make both x and y zero.

Try

while(x!= 0 && y!= 0)

Now, the loop will keep going if x isn't zero AND if y isn't zero. Making x zero, or making y zero, will break the loop.

[Ben Duncan]

Thank you so much!

Yeah, the loop did sound a bit weird in my head too. (It didn't make any sense in English.)

The returnedValue worked!

You're the best!