Thanks for the vote of confidence, Ross. hah. *shrug* At any rate, I was wrong about one thing. Mis-remembered something about converting a string to a int. It doesn't pull all numbers out of the string, it only pulls leading numbers. $address = "123 Main St Apt 45"; echo intval($address); outputs "123" not "12345" But as explained, the lack of numbers (specifically at the front end of the string) produces a numerical zero. As to "numbers should be converted to strings" that was sort of my initial thoughts when I started using PHP, but now that I've used it for a while, I think the "convert to lowest common denominator" method works better. Either way, it was a judgement call on the part of the PHP development team and it's how PHP operates. So at this point it's kind of like saying "This house really should have a basement" after the house is built. Maybe there's a good reason why they didn't put a basement in to start with and technically it's possible to add a basement if they changed their mind, but at what cost. At any rate, known, predictable and intentional behavior is not a bug. -TG = = = Original message = = = I'm yet to be convinced it isn't a bug. I suspect it is a bug that has been around so long that they can't afford to fix it or it may break many applications that for various peculiar reasons rely on it to behave as it does for their code to work. For those who have tried to defend its behaviour, this is my logic. 1. The == operator means, by definition, "don't worry about variable 'type', just compare the values" (This is probably the single thing I love about PHP more than anything else) 2. If the numeric variable $x is given ANY other numeric value other than zero, the logic behaves correctly as you read it So it is irrational for program logic to vary between a zero value and, for aguments sake, a numeric value of 42. Regarding specifically TG's explanation below, I believe he is wrong. If you compare a numeric type and a string type using ==, PHP should convert the number to a string and compare the two from there. Anyway, not expecting any answers to this, just a point of note and a strange quirk to keep at the back of your head when consciously comparing numeric / string variables. Ross tg-php@xxxxxxxxxxxxxxxxxxxxxx wrote: > It's because PHP is trying to convert different var types into a common var type and then compare them when you use ==. === means compare value AND type so that's why it fails. > > Your string, 'Some kind of string' is getting converted down to the lowest common denominator, an int. Since there are no numbers in the string to grab onto, it gets converted to nothing, an int value of zero. > > If you had $x = "0" or if $y had contained numbers at all, it wouldn't have passed. > > But this is why when you use $x.'' it works properly because now you have "0<empty string>", it's been converted to a string value "0". Good catch on that though, shows good methodical debugging :) > > So in the future, either use === or be extra aware of your variable types and make sure you're comparing properly. > > Good luck! > > -TG > > = = = Original message = = = > > $x = 0; // Numeric zero > $y = 'Some kind of string'; > > if ($x == $y) echo 'they equal using =='; > if ($x === $y) echo 'they equal using ==='; > > The above will echo 'they equal using =='. > > The values don't look very equal to me. > > Can anyone explain the logic behind this? > > I'm heading home now but look forward to your explanations tomorrow. > > PS > > Incidently, to 'fix' it so it behaves as it should, you can code: > > if ($x.'' == $y.'') echo 'this will not print and all is good.'; > > Regards .. Ross > > > ___________________________________________________________ > Sent by ePrompter, the premier email notification software. > Free download at http://www.ePrompter.com. > > -- PHP Windows Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php ___________________________________________________________ Sent by ePrompter, the premier email notification software. Free download at http://www.ePrompter.com. -- PHP Windows Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
