php: array_diff_assoc and the order of parameters

This took a while till I found out: They actually do matter!
Even worse: The manual says so!!!! Just that I was to stupid to read it.
Lesson learned. No more guessing, no more quick reading!

<?
$a = array(
    'x' => 'x',
    'y' => 'y',
    'z' => 'z',
    't' => 't',
);

$b = array(
    'x' => 'x',
    'y' => 'y',
    'z' => 'z',
    't' => 't',
    'g' => 'g',
);

print_r(array_diff_assoc($a, $b));
print_r(array_diff_assoc($b, $a));
?>

This will output:

Array
(
)
Array
(
    [g] => g
)

Comment

1. see http://www.php.net/manual/en/function.array-diff-assoc.php
   
   array_diff_assoc() returns an array containing all the values from array1 that are not present in any of the other arguments.
   — ShiningRay    12 April, 4:37am    #
2. I know! Stupidity never dies, not even in oneself. However, I was assuming it would behave like a unix diff.
   — Pascal Opitz    12 April, 9:57am    #

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