From: my-design at gmx dot net
Operating system: Slackware 11; Kernel 2.6.15.6
PHP version: Irrelevant
PHP Bug Type: Documentation problem
Bug description: Type casting from float into string
Description:
------------
Casting from float into string rounds the number without a notice.
There seems to be some difference between rounding precision for an string
casting and internal float storage precision; that is perhaps not a bug in
float handling itself, but is totally unexpected and is a great error
source for some scripts.
In the above example the value for $x was originally integer 19, stored
into the database as float and restored later as given. There is no method
to see the difference directly, only in serialised data.
Tested PHP versions: 4.4.4 , 4.3.11
Reproduce code:
---------------
$x=18.99999999999999289457264239899814128875732421875;
print "x=${x}\n";
$a=array();
$a[$x]=$x;
print_r($a);
Expected result:
----------------
x=18.999999999999
Array
(
[18] => 18.999999999999
)
Actual result:
--------------
x=19
Array
(
[18] => 19
)
--
Edit bug report at http://bugs.php.net/?id=40280&edit=1
--
Try a CVS snapshot (PHP 4.4):
http://bugs.php.net/fix.php?id=40280&r=trysnapshot44
Try a CVS snapshot (PHP 5.2):
http://bugs.php.net/fix.php?id=40280&r=trysnapshot52
Try a CVS snapshot (PHP 6.0):
http://bugs.php.net/fix.php?id=40280&r=trysnapshot60
Fixed in CVS: http://bugs.php.net/fix.php?id=40280&r=fixedcvs
Fixed in release:
http://bugs.php.net/fix.php?id=40280&r=alreadyfixed
Need backtrace: http://bugs.php.net/fix.php?id=40280&r=needtrace
Need Reproduce Script: http://bugs.php.net/fix.php?id=40280&r=needscript
Try newer version: http://bugs.php.net/fix.php?id=40280&r=oldversion
Not developer issue: http://bugs.php.net/fix.php?id=40280&r=support
Expected behavior: http://bugs.php.net/fix.php?id=40280&r=notwrong
Not enough info:
http://bugs.php.net/fix.php?id=40280&r=notenoughinfo
Submitted twice:
http://bugs.php.net/fix.php?id=40280&r=submittedtwice
register_globals: http://bugs.php.net/fix.php?id=40280&r=globals
PHP 3 support discontinued: http://bugs.php.net/fix.php?id=40280&r=php3
Daylight Savings: http://bugs.php.net/fix.php?id=40280&r=dst
IIS Stability: http://bugs.php.net/fix.php?id=40280&r=isapi
Install GNU Sed: http://bugs.php.net/fix.php?id=40280&r=gnused
Floating point limitations: http://bugs.php.net/fix.php?id=40280&r=float
No Zend Extensions: http://bugs.php.net/fix.php?id=40280&r=nozend
MySQL Configuration Error: http://bugs.php.net/fix.php?id=40280&r=mysqlcfg
