Re: [PHP] Re: unexpected array_diff output

[Frederic Noyer]

On 30 avr. 04, at 11:00, Torsten Roehr wrote:

"Frederic Noyer" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
Hello there !
I am trying to fill and then compare two arrays: one filled by a
foreach construct, and the second by a while construct.
I check both with a print_r to be sure that both are correctly filled
(which seems to be the case). But then, when I try to compare them 
with
a array_diff , the result is incoherent (at least to me...). I have
tried several variant, but I don't understand what's wrong. Sure you
guys can tell me where is my mistake.

Here is the code:

<?

// creates first array (from a _POST[''] )
foreach ($_POST['input_auteur'] AS $aut_ligne) {
$part_ligne = explode(",",$aut_ligne);
$arr1[] = (string) $part_ligne['2'];
}
echo "Array from POST :";
print_r ($arr1);
// creates second array (from SQL query)
$sqlListAut = 'SELECT aut_id FROM mr_ecrit WHERE doc_id = ' .
$_GET['docu'];
$resultListAut = mysql_query($sqlListAut);
while ($recListAut = mysql_fetch_array($resultListAut)) {
$arr2[] = (string) $recListAut['aut_id'];
}
echo "Array from SQL:<BR>";
print_r ($arr2);
// comparing both arrays to detect if there is elements in the first
array which are not present in the second array $result =
array_diff($arr1, $arr2);
echo "array_diff results :";
print_r($result);
?>
Here is a typical output:
__________________________________________
Array from POST: Array (  [0] => 2  [1] => 3  [2] => 4 )
Array from SQL : Array (  [0] => 3  [1] => 4 )
******
array_diff results : Array (  [0] => 2  [1] => 3  [2] => 4 )
__________________________________________
As you can see, the array_diff seems to always return all elements of
the first array.
I think this is correct because the 3 key/value pairs from the first 
array
are NOT in the second one. I think the combination of key and value are
relevant for array_diff().

So if you had:

Array from POST: Array (  [0] => 2  [1] => 3  [2] => 4 )
Array from SQL : Array (  [0] => 2  [1] => 3 )
******
The diff would be:
array_diff results : Array (  [2] => 4 )
Ok, but when I give the function this input

Array from POST: Array (  [0] => 2 )

Array from SQL : Array (  [0] => 2 )
----
The output I get is:

the diff between both : Array (  [0] => 2 )

Why is it not and empty output ?  Which is not what I have understand 
the array_diff should do (or maybe I didn't understand what the 
function should do).
Thanks again for your kind help,

Frederic Noyer

PS: version of PHP is 4.3

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