#31285 [Opn->Bgs]: something about operator precedence

ID: 31285 Updated by: derick@php.net Reported By: geometer at ua dot fm -Status: Open +Status: Bogus Bug Type: Math related Operating System: * PHP Version: Irrelevant New Comment: I can't explain why we have this, but this bug report is not meant for those discussions (try the internals mailinglist, also I doubt it'll get you very far). Nevertherless, there is no change that we'll ever change this because of backward compatibility reasons. Previous Comments: ------------------------------------------------------------------------ [2004-12-24 13:23:13] geometer at ua dot fm Description: ------------ hello it's not a bug, but an UNREASONABLE peculiarity of PHP (all versions). the peculiarity may be a reason of "strange" behavior of a script and errors may take a lot of time for their fixing. i say about precedence of some operators. let's take a look on precedence of bitwise operator "&" and comparison one "==". let me need to find out is number of the lowest significant bits in $x is less then 8 or not. as it can be done in other programming languages, i use the following construction: if ($x&0x7f==$x) {ok} else {not ok} if you try to use such a construction in a script you would be amazed, because $x&0x7f==$x IS TRUE IF AND ONLY IF $x IS EQUAL TO 0x7f! if you try to use 0x7f&$x==$x instead of original condition, you would be amazed twice, because 0x7f&$x==$x IS ALWAYS TRUE. and what the reason of this tricks? the reason is the precedence of "&" is LOWER than one of "==". so, i HAVE to write ($x&0x7f)==$x or (0x7f&$x)==$x, because taking into account the precedence one obtains: $x&0x7f==$x <=> $x&(0x7f==$x) 0x7f&$x==$x <=> 0x7f&($x==$x) such behavior is not common in programming and in mathematics. and even if i aware about the precedence, i can make a mistake "on the fly" in expression (do you like to print additional parenthesis? ;)). so, what's the reason of such particuliarly in PHP? may be it needs to be removed from the following releases? Reproduce code: --------------- <? $x = 0x76; echo $x&0x7f==$x; echo "\n"; echo 0x7f&$x==$x; ?> Expected result: ---------------- 1 1 Actual result: -------------- 0 1 ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=31285&edit=1