while (cin >> NumData >0)

[ramako]

As written in the title, this won't work. If I try writing a 0 it DOES goes into the loop.
Can't it be done inside the while?

[coder777]

Yes that doesn't work. You're trying two things at once. What about

while (cin >> NumData)
{
  if(NumData >0)
  {
     // do something
  }
}

[ramako]

It did work with reading from files, haha .

Thanks for your help ;)

[S6k9GNh0]

You can do something like "(cin >>myStreamable) >> myStreamDataHolder" though. It's rather hard to read but some people do it.

[D80DSL3A]

Ah, a use for the comma operator!

int main(void)
{
	int NumData;
	cout << "Enter NumData: ";
	while( cin >> NumData, NumData > 0 )
		cout << "Enter NumData: ";

	cout << "Bye-bye" << endl;
	return 0;	
}

EDIT: All statements in the parentheses are executed, but only the last is used for the logical test.
You can even put the prompt in there!

int main(void)
{
	int NumData;	
	while( cout << "Enter NumData: ", cin >> NumData, NumData > 0 );
	cout << "Bye-bye" << endl;
	return 0;	
}

[S6k9GNh0]

Wow, that's an interesting use indeed. You know, I didn't even know there was a comma operator until I was looking at how boost assign worked yesterday.

[Zhuge]

That does defeat the point of having the read inside of the while loop though, to check for an error in reading via cin.

[D80DSL3A]

True, input validation can't be done with that method.
I just meant to show how what ramako was attempting to do could be done.

@ramako. If a non-integer value is entered then cin will fail and there will be no way to clear that condition. An infinite loop results. The method is therefore NOT recommended.