Bug #14805 Updated: array_unique works opposed to the manual
ID: 14805
Updated by: venaas
Reported By: pgerzson@freestart.hu
Old Status: Open
Status: Assigned
Bug Type: Arrays related
Operating System: MS Windows 98 PWS 4.0
PHP Version: 4.1.1
Old Assigned To:
Assigned To: venaas
New Comment:
array_unique() uses qsort internally. Provided qsort doesn't
change order of items that are equal, array_unique() should
work as documented. Until recently the systems own qsort
was used, giving different behavior on different systems.
With latest PHP (in CVS) we use our own qsort which doesn't
preserve order of equal items either. I'll either get that
qsort changed, or I will write a new slower array_unique()
that doesn't depend on qsort behavior.
Previous Comments:
------------------------------------------------------------------------
[2002-01-09 12:18:16] pgerzson@freestart.hu
I tested the examples with PHP 4.1.1 on Apache 1.3.9 under debian
stable. array_unique() does preserve the *first* key
of every related value in this environment.
Simone Cortesi <cortesi@php.net> stated on phpdoc list:
" On my PHP Version 4.0.6 on System Windows 95/98 4.10
" (as it reads with phpinfo), I get...
what I got, but
" On the same machine using Cygwin and PHP/4.0.8-dev
" I get:
the expected result (returning with the first keys).
------------------------------------------------------------------------
[2002-01-02 13:20:30] pgerzson@freestart.hu
I forgot to mention that there may be something wrong with
array_unique itself. There are three values of 3 considered equal in
the example above:
2 => "3"(string), 4 => 3(int), 5 => "3" (string)
[manual]
" Two elements are considered equal if and only if (string)
" $elem1 === (string) $elem2. In words: when the string
" representation is the same."
Why does array_unique use the index 4 in this case?
(It's neither the first nor the latest key of value 3)
------------------------------------------------------------------------
[2002-01-02 12:48:29] pgerzson@freestart.hu
The manual (recent version from cvs) states that :
" array_unique() will keep the first key encountered for every value,
and ignore all following keys. "
I've tested the two examples in this page and I've found
this statement is not true.
<?php
$input = array (4,"4","3",4,3,"3");
$result = array_unique ($input);
var_dump($result);
?>
output: /* PHP 4.0.6 Win'98 PWS */
array(2) {
[3]=>
int(4)
[4]=>
int(3)
}
but the manual says it should print:
array(2) {
[0]=>
int(4)
[1]=>
string(1) "3"
}
As you can recognize the latest keys are preserved
for both value 4 and 3.
------------------------------------------------------------------------
Edit this bug report at http://bugs.php.net/?id=14805&edit=1
Thread (5 messages)