Req #39579 [Nab]: Comparing zero & string values in boolean comparison has unexpected behaviour

Edit report at https://bugs.php.net/bug.php?id=39579&edit=1 ID: 39579 User updated by: iain at workingsoftware dot com dot au Reported by: iain at workingsoftware dot com dot au Summary: Comparing zero & string values in boolean comparison has unexpected behaviour Status: Not a bug Type: Feature/Change Request Package: Variables related Operating System: FreeBSD 6.1 PHP Version: 5.2.0 Block user comment: N Private report: N New Comment: Hi mirroredfate at gmail dot com, I really don't think this should be changed. Take a look at my note above about why this happens, it's because in one case the string is cast as boolean, and in another case cast as an int. Changing this would require either: a) Changing the type that you cast a variable to when you do if($var) to something other than boolean or changing the way that types are cast when comparing a string and an int to each other OR; b) Changing the value that a string is cast to when cast as either a boolean or an int, to be consistent Both of these changes would wreak unspeakable havoc on existing applications, and probably wouldn't make any tremendous difference overall to the uninitiated. HOWEVER, I do think that it would be acceptable to emit a NOTICE when a string is implicitly cast to (int) during a comparison using == and suggesting they use an explicit type cast or strict equals to suppress the notice (see my comments above). Previous Comments: ------------------------------------------------------------------------ [2013-10-22 18:42:18] mirroredfate at gmail dot com > It's not a problem -- it's a feature, and it's documented at the address > I've just quoted And I could document a webserver sometimes crashing when you click a button and call it a "feature", but that doesn't make it so. This is clearly counter-intuitive behavior and should be beaten to death with an iron rod after being water-boarded. It is terrible. If you are defending this, you should probably take a long, hard look at your life and your principles. Making zero equal any string is just wrong. I completely goes against how PHP operates in every other instance, and no doubt causes developers no end of distress and frustration. It's a feature like how getting beaten up in a dark alley is a feature of that alley. This needs to be fixed, people. ------------------------------------------------------------------------ [2013-07-03 00:36:56] iain at workingsoftware dot com dot au Hey xtalviper, the reason it does this is because in the case of: if($string) then the string is cast to a boolean. If you do: if($int == $string) then the string is cast to an int. You can see this more clearly by doing this: <?php $boolstring = (boolean)"string"; $intstring = (int)"string"; var_dump($boolstring); var_dump($intstring); ------------------------------------------------------------------------ [2013-07-02 21:31:57] xtalviper at yahoo dot com Here's the basic problem of logic that doesn't follow for me: If I do if(0) { //...is false, this will never run } and I do if("string") { //...is true, will always run } Then how the hell can true == false ------------------------------------------------------------------------ [2013-02-15 10:08:27] radamanf at gmail dot com Hi Nick, Thanks for your answers on both related bugs. I apologize for my expressions. But I'm still thinking this bug should be fixed one day, maybe on later day when a few backwards compatible bugs will be found, so it makes more sense to fix it as a bunch. I hear that PHP 5.3 was breaking release and some old code was not working since, it was the right time to fix this bug. The general logic should be: Convert less complicated variable type into more complicated type, so convert Int up to String not bringing String down to Int. This need to be universal and according to KISS logic. If geeks need to use strings for octal or hexadecimal then they know what they are doing and need to cast such string as Int! To bring string down to Int. v dot picture at free dot fr -> " Then why would PHP decide to do that in a string context ? I mean, when I compare two strings I don't expect PHP to convert everything to numbers ! "10" == "1e1" => true Sorry folks, this really seems like a string context to me. " Someone need to write a great exploit to hack into eCommerce shops and produce unseen damage across the Globe :) then this will not be funny at all. I wish this patch could happen one day! Temporarily it could be at least a Warning, Iain suggested to give a notice, but I believe this bug got a great hidden potential. ------------------------------------------------------------------------ [2013-02-14 22:52:25] iain at workingsoftware dot com dot au Sorry I meant to submit this as "Feature/Change Request" but submitted the form without a password and it changed back to "bug". ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=39579 -- Edit this bug report at https://bugs.php.net/bug.php?id=39579&edit=1