From: daniel dot oconnor at gmail dot com
Operating system: Irrelevant
PHP version: 5.2.4
PHP Bug Type: Feature/Change Request
Bug description: var_dump() should render more precise floats
Description:
------------
var_dump() does not show the actual value of floats; but rather performs
rounding before rendering.
This can lead to hard to decipher loss of precision bugs. If you then use
var_dump() to try to compare output, you aren't going to find the *actual*
values of the numbers you are comparing.
For this reason, I'd like to ask var_dump() renders the complete
representation of the number; where needed in scientific notation.
Reproduce code:
---------------
<?php
function variance($a, $b) {
return (double)100.00 - (double)(($a/$b) * 100.00);
}
var_dump(12.99); //12.99
var_dump(variance(87.01, 100.00)); //12.99
var_dump(variance(87.01, 100.00) - 12.99); //difference
<-5.3290705182008E-15>
Expected result:
----------------
---------- php ----------
float(12.99)
float(12.99) // should be 12.99 + -5.3290705182008E-15
float(-5.3290705182008E-15)
Output completed (0 sec consumed) - Normal Termination
Actual result:
--------------
---------- php ----------
float(12.99)
float(12.99)
float(-5.3290705182008E-15)
Output completed (0 sec consumed) - Normal Termination
--
Edit bug report at http://bugs.php.net/?id=42635&edit=1
--
Try a CVS snapshot (PHP 4.4):
http://bugs.php.net/fix.php?id=42635&r=trysnapshot44
Try a CVS snapshot (PHP 5.2):
http://bugs.php.net/fix.php?id=42635&r=trysnapshot52
Try a CVS snapshot (PHP 6.0):
http://bugs.php.net/fix.php?id=42635&r=trysnapshot60
Fixed in CVS: http://bugs.php.net/fix.php?id=42635&r=fixedcvs
Fixed in release:
http://bugs.php.net/fix.php?id=42635&r=alreadyfixed
Need backtrace: http://bugs.php.net/fix.php?id=42635&r=needtrace
Need Reproduce Script: http://bugs.php.net/fix.php?id=42635&r=needscript
Try newer version: http://bugs.php.net/fix.php?id=42635&r=oldversion
Not developer issue: http://bugs.php.net/fix.php?id=42635&r=support
Expected behavior: http://bugs.php.net/fix.php?id=42635&r=notwrong
Not enough info:
http://bugs.php.net/fix.php?id=42635&r=notenoughinfo
Submitted twice:
http://bugs.php.net/fix.php?id=42635&r=submittedtwice
register_globals: http://bugs.php.net/fix.php?id=42635&r=globals
PHP 3 support discontinued: http://bugs.php.net/fix.php?id=42635&r=php3
Daylight Savings: http://bugs.php.net/fix.php?id=42635&r=dst
IIS Stability: http://bugs.php.net/fix.php?id=42635&r=isapi
Install GNU Sed: http://bugs.php.net/fix.php?id=42635&r=gnused
Floating point limitations: http://bugs.php.net/fix.php?id=42635&r=float
No Zend Extensions: http://bugs.php.net/fix.php?id=42635&r=nozend
MySQL Configuration Error: http://bugs.php.net/fix.php?id=42635&r=mysqlcfg
