Sum of Multiples of 3 and 5 Below 1000 - Simple C++ Programming Question

[Finkle]

I'm teaching myself C++ and am stuck on this VERY simple problem. I'm not sure what's wrong with my code.

The problem is from https://projecteuler.net/ if anyone is wondering.

Homework Statement

If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.

Find the sum of all the multiples of 3 or 5 below 1000.

Homework Equations

The Attempt at a Solution

#include <iostream>
using namespace std;

int main()
{
	int num, add;

	num = 1;
	add = 0;
	while(num < 1001)
	{
		if(num % 3 == 0 || num % 5 == 0)
		{
			add = num + add;
		}
		num = num + 1;
	}
	cout<<add<<endl;
	return 0;
}

The answer I get from this is 234168 but the site says this is wrong.

 

[Finkle]

Annnnd I figured out what I did wrong. The problem states below rather than up to 1000. It included 1000 in the answer so I just subtract that and be on my way.

If there are any bad habits that are in my code, I would like to know just so I don't continue using it.

Thanks.