#47092 [Opn]: Bitwise operation number overflow

ID: 47092 User updated by: erik at ekriirke dot com Reported By: erik at ekriirke dot com Status: Open Bug Type: MySQLi related Operating System: LAMP, WAMP, WIMP PHP Version: 5.2.8 New Comment: I meant to say "32bit math" is touchy, sorry Previous Comments: ------------------------------------------------------------------------ [2009-01-13 22:02:35] erik at ekriirke dot com Just an addendum; This is only when working with MySQL (from what I have tested), absolutes do not have this problem (eg echo dechex(0x80001234);) ------------------------------------------------------------------------ [2009-01-13 22:00:37] erik at ekriirke dot com Description: ------------ This happens the same on Linux (RHE5) and Windows (Server2K,XPPro) Differing versions of MySQL as well (5.0.51a, 5.1.11) Using either MySQLi or MySQL extensions I have a table with an UNSIGNED INTEGER column. The value in the column has a value where MSB (31) is set (0x80000000 and higher). Selecting this value into an array via either mysql_fetch_assoc, mysql_fetch_row (and mysqli variant) stores the value correctly as displayed by either a print_r or echo'ing directly. Should I perform a math operation (+-*/) the result is correct. Should I perform a bitwise operation or function the answers are wrong. It appears doing so internally changes the selected value to 0x7FFFFFFF no matter its original value as long as bit 31 is set. However, if I perform math on the value THEN a bitwise operation, the result is correct. Now, I know the MSB is a touchy subject in 31bit math, but there is inconsistency here. Reproduce code: --------------- $q=mysql_query("SELECT val FROM test"); // val is an UNSIGED INT containing a value with MSB set. Ex: 2147488308 (0x80001234) $a=mysql_fetch_assoc($q); echo $a['val'],"<br>\n"; //2147488308 - correct echo dechex($a['val']),"<br>\n"; //7fffffff - wrong echo $a['val']+0,"<br>\n"; //2147488308 - correct echo $a['val']+1,"<br>\n"; //2147488309 - correct echo $a['val']|0,"<br>\n"; //2147483647 - wrong echo dechex($a['val']+0),"<br>\n"; //80001234 - correct echo $a['val']&1,"<br>\n"; //1 - wrong echo ($a['val']+0)&1,"<br>\n"; //0 - correct /*** Workaround ***/ $a['val']+=0; //as long as some kind of math was performed it functions correctly afterward echo $a['val']|0,"<br>\n"; //2147488308 or -2147478988 - correct echo $a['val']&1,"<br>\n"; //0 - correct echo dechex($a['val']),"<br>\n"; //80001234 - correct Expected result: ---------------- 2147488308 80001234 2147488308 2147488309 -2147478988 80001234 0 0 -2147478988 0 80001234 Actual result: -------------- 2147488308 7fffffff 2147488308 2147488309 2147483647 80001234 1 0 -2147478988 0 80001234 ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=47092&edit=1