ID: 6019
Updated by: [EMAIL PROTECTED]
-Summary: Error with equal operator when comparing certain
values
Reported By: [EMAIL PROTECTED]
Status: Analyzed
Bug Type: Feature/Change Request
Operating System: NT4.0
PHP Version: 4.0.1pl2
New Comment:
updating summary.
Previous Comments:
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[2000-08-08 10:34:55] [EMAIL PROTECTED]
the precisions are machine-/build-dependant
so we can't document them in the manual
maybe we can add a section to phpinfo()
and/or some constants as in limits.h
for MIN/MAX values for integer and float
values
(passed on to feature request)
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[2000-08-08 09:37:36] [EMAIL PROTECTED]
I think this limitation isn´t mentioned anywhere clearly,
transforming into docu bug
In fact I don´t know where to look for it and I think the
php.ini precision settings has nothing to do with it...
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[2000-08-08 09:25:26] [EMAIL PROTECTED]
verified, replacing == with === in the third block will
produce 0, what is correct
for any reason the comparison is done corretly withing
strings, I think you won´t have to switch to bcmaths
functions for these tiny doubles, using var_dump() reveals
that they´re correctly stored in $GLOABLS
resumé: PHP performs return only 0,2,4 differences not 1,3,5
dealing with large numbers
example:
echo 9834567891230000-9834567891229999; // return2 s, should 1
echo 9834567891230000-9834567891230001; // returns 0, should -1
and so on
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[2000-08-08 09:07:23] [EMAIL PROTECTED]
1. Use === when you are interested in string-to-string comparison.
2. PHP has precision limits, if you need more precision please use bc
extension.
------------------------------------------------------------------------
[2000-08-08 08:59:54] [EMAIL PROTECTED]
When comparing certain numbers using the equals operator (==) it
returns true even though numbers are not equal. It doesnt matter if
number is duoble or string.
It only happens when number is 16 digit. 15 & 17 digits is OK.
Using strcmp() doesnt produce this error.
Example:
<?php
$one = 9834567891230000; //double
$two = 9834567891230000; //double
print(($one == $two)); //returns 1 (OK)
$one = 9834567891230000; //double
$two = 9834567891230001; //double
print(($one == $two)); //returns 1 (wrong)
$one = "9834567891230000"; //string
$two = "9834567891230001"; //string
print(($one == $two)); //returns 1 (wrong)
$one = 9834567891230000; //double
$two = 9834567891230002; //double
print(($one == $two)); //returns 0 (OK)
$one = 1834567891230000; //double
$two = 1834567891230001; //double
print(($one == $two)); //returns 0 (OK)
?>
I have tried under diffrent versions of php both under linux and NT4.0
with the same result.
latest: 4.0.1pl1 NT4.0 precompiled downloaded from php.net
Can send php.ini if you want.
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Edit this bug report at http://bugs.php.net/?id=6019&edit=1
