[PHP] unexpected array_diff output
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) $recListAut['aut_id'];
}
echo "Array from SQL:";
print_r ($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.
Thanks for your help.
Best regards,
Fred Noyer
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Re: [PHP] Re: unexpected array_diff output
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) $recListAut['aut_id'];
}
echo "Array from SQL:";
print_r ($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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Re: [PHP] Re: unexpected array_diff output
On 30 avr. 04, at 11:00, Torsten Roehr wrote: 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(). As I have understand only the array_diff_assoc function does that. see php.net: "Description array array_diff_assoc ( array array1, array array2 [, array ...]) array_diff_assoc() returns an array containing all the values from array1 that are not present in any of the other arguments. Note that the keys are used in the comparison unlike array_diff()." Fred 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 ) Regards, Torsten -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] Re: unexpected array_diff output
On 30 avr. 04, at 11:31, Torsten Roehr wrote: "Frederic Noyer" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] On 30 avr. 04, at 11:00, Torsten Roehr wrote: 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(). As I have understand only the array_diff_assoc function does that. see php.net: "Description array array_diff_assoc ( array array1, array array2 [, array ...]) array_diff_assoc() returns an array containing all the values from array1 that are not present in any of the other arguments. Note that the keys are used in the comparison unlike array_diff()." So array_diff() seems to be for arrays where the key is not defined so that only values are recognized. Regards, Torsten Any ideas what this implies in termes of code ? You mean, I should not fill my array with values this way ? "$arr2[] = (string) $recListAut['aut_id'];" Because this is precisely the way to fill it without specifying the key. see www.php.net: http://ch2.php.net/manual/en/language.types.array.php Regards, Fred -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] unexpected array_diff output
On 30 avr. 04, at 12:11, Ford, Mike [LSS] wrote:
On 30 April 2004 09:47, Frederic Noyer wrote:
Hello there !
I am trying to fill and then compare two arrays: one
filled by a
foreach construct, and the second by a while construct.
I check both with a print_r to be sure that both are correctly filled
(which seems to be the case). But then, when I try to compare
them with
a array_diff , the result is incoherent (at least to me...). I have
tried several variant, but I don't understand what's wrong. Sure you
guys can tell me where is my mistake.
Here is the code:
// creates first array (from a _POST[''] )
foreach ($_POST['input_auteur'] AS $aut_ligne) {
$part_ligne = explode(",",$aut_ligne);
$arr1[] = (string) $part_ligne['2'];
}
echo "Array from POST :";
print_r ($arr1);
I don't have any great insight into what appear to be your odd
array_diff()
results, but try using var_dump() instead of print_r() -- it will give
you
more information about *exactly* what values are stored in the arrays,
and
it may just be that you'll spot an odd discrepancy.
Cheers!
Mike
Thanks, Mike ! That was the correct answer. In one of the array there
was always a "space" in front of the digit (ex: " 2"). The comparison
was then corrupted because of this. I never used var_dump() before, but
it is far more precise. Thanks for the hint!
Thanks to you too, Thorsten for your kind help.
Best regards,
Fred
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