ID: 47092
Updated by: [email protected]
Reported By: erik at ekriirke dot com
Status: Open
-Bug Type: MySQLi related
+Bug Type: Unknown/Other Function
Operating System: *
PHP Version: 5.2.8
New Comment:
This is not a problem in MySQL, it is a PHP bug or dechex bug.
Here is an example. First, we use a number, than a string with a
number.
and...@winnie:~/scripts$ php -r '$a=2147488308;print_r($a);echo
"\n";print_r($a+1);echo "\n";print_r(dechex($a));echo "\n";'
2147488308
2147488309
80001234
and...@winnie:~/scripts$ php -r '$a="2147488308";print_r($a);echo
"\n";print_r($a+1);echo "\n";print_r(dechex($a));echo "\n";'
2147488308
2147488309
7fffffff
Previous Comments:
------------------------------------------------------------------------
[2009-01-13 22:22:13] erik at ekriirke dot com
I meant to say "32bit math" is touchy, sorry
------------------------------------------------------------------------
[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
