#23110 [Opn->Csd]: Ugly behaviour of == (and ===)

ID: 23110 Updated by: vrana@php.net Reported By: kyrael at web dot de -Status: Open +Status: Closed Bug Type: Documentation problem Operating System: Linux PHP Version: 4.3.1 New Comment: This bug has been fixed in the documentation's XML sources. Since the online and downloadable versions of the documentation need some time to get updated, we would like to ask you to be a bit patient. Thank you for the report, and for helping us make our documentation better. "If you compare integer with the string, the string is converted to number. If you compare two numerical strings, they are compared as integers. These rules are valid also for the switch statement." + example: <?php var_dump(0 == "a"); // 0 == 0 -> true var_dump("1" == "01"); // 1 == 1 -> true switch ("a") { case 0: echo "0"; break; case "a": // never reached because "a" is already matched with 0 echo "a"; break; } ?> Previous Comments: ------------------------------------------------------------------------ [2004-05-22 11:20:55] nlopess@php.net See also #20726. ------------------------------------------------------------------------ [2004-02-04 18:15:12] tgrey at supercomputerinc dot com highly illogical indeed. if the types differ, how could the values be considered equal? when working with functions that could have different input types this behaviour is disasterous. it seems to be counterproductive to loose variable types, since a data type check has to be added. working around is often possible, but if i wanted to code around my *** to get to my elbow i'd be using perl. imho this behavior needs some strong reconsideration. very simple example: <? $in="blah"; if($in==0) echo "zero: $in"; else echo "not zero: $in"; ?> or worse yet: <? function test($in=0) { switch($in) { case 0: echo "zero: $in"; break; case "blah": // never reached! echo "blah: $in"; break; default: echo "default: $in"; break; } } test(); test("blah"); test(2); ?> ------------------------------------------------------------------------ [2003-05-02 13:10:29] nicos@php.net This will not change, the documentation team needs to be clear on that. We don't have '===' for nothing. ------------------------------------------------------------------------ [2003-04-08 06:57:38] kyrael at web dot de Btw, in switch you can't use strcmp or ===, because switch seems to use ==. ------------------------------------------------------------------------ [2003-04-08 06:43:46] kyrael at web dot de <?php list($var1,$var2)=array("1e1","10"); var_dump($var1);var_dump($var2); var_dump($var1==$var2); var_dump($var1===$var2); ?> string(3) "1e1" string(2) "10" bool(true) bool(false) This behaviour is ugly - both operands are strings, and they are clearly not equal. '1e0' and '1.0' and '1' are "equal" too. Same with '3.20' and '3.2'. Does PHP think i am stupid and unable to type numbers when i want them? According to the manual, == returns true if the two operands are equal, and === returns true if the operands are equal and of the same type. == says they are equal, and according to var_dump they are both strings - why doesn't === return true then? So this behaviour is neither logical nor documented. String comparison, even with == when both operands are strings, should return 'equal' if and only if the strings are really equal. Wouldn't be PHP5 a chance to change this? ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=23110&edit=1