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(PHP 5)
array_udiff — Ermittelt den Unterschied zwischen Arrays mittels einer Callbackfunktion für den Datenvergleich
array_udiff() gibt ein Array mit allen Werten von array1, welche in keinem der anderen Argumente enthalten sind, zurück. Beachten Sie, dass Schlüssel erhalten bleiben. Für den Vergleich der Daten wird data_compare_func herangezogen. Diese muss einen Integer kleiner als, genau gleich oder größer als Null zurückgeben, wenn das erste Argument entsprechend als kleiner, gleich oder größer als das Zweite betrachtet wird. Dies ist anders als array_diff(), in der eine eingebaute Funktion für den Vergleich der Indizes verwendet wird.
Beispiel #1 array_udiff() Beispiel
<?php
class cr {
private $priv_member;
function cr($val)
{
$this->priv_member = $val;
}
function comp_func_cr($a, $b)
{
if ($a->priv_member === $b->priv_member) return 0;
return ($a->priv_member > $b->priv_member)? 1:-1;
}
}
$a = array("0.1" => new cr(9), "0.5" => new cr(12), 0 => new cr(23), 1=> new cr(4), 2 => new cr(-15),);
$b = array("0.2" => new cr(9), "0.5" => new cr(22), 0 => new cr(3), 1=> new cr(4), 2 => new cr(-15),);
$result = array_udiff($a, $b, array("cr", "comp_func_cr"));
print_r($result);
?>
Das oben gezeigte Beispiel erzeugt folgende Ausgabe:
Array
(
[0.5] => cr Object
(
[priv_member:private] => 12
)
[0] => cr Object
(
[priv_member:private] => 23
)
)
Hinweis: Bitte beachten Sie, dass diese Funktion nur eine Dimension eines n-dimensionalen Arrays überprüft. Natürlich können Sie tiefere Dimensionen prüfen, indem Sie array_udiff($array1[0], $array2[0], "data_compare_func"); verwenden.
Siehe auch array_diff(), array_diff_assoc(), array_diff_uassoc(), array_udiff_assoc(), array_udiff_uassoc(), array_intersect(), array_intersect_assoc(), array_uintersect(), array_uintersect_assoc() und array_uintersect_uassoc().
Note that php does the string conversion *before* sending the values to the callback function.
It is not stated, by this function also diffs array1 to itself, removing any duplicate values...
Re: "convoluted"
I think the point being made is that array_udiff() can be used not only for comparisons between homogenous arrays, as in your example (and definitely the most common need), but it can be used to compare heterogeneous arrays, too.
Consider:
<?php
function compr_1($a, $b) {
$aVal = is_array($a) ? $a['last_name'] : $a;
$bVal = is_array($b) ? $b['last_name'] : $b;
return strcasecmp($aVal, $bVal);
}
$aEmployees = array(
array('last_name' => 'Smith',
'first_name' => 'Joe',
'phone' => '555-1000'),
array('last_name' => 'Doe',
'first_name' => 'John',
'phone' => '555-2000'),
array('last_name' => 'Flagg',
'first_name' => 'Randall',
'phone' => '666-1000')
);
$aNames = array('Doe', 'Smith', 'Johnson');
$result = array_udiff($aEmployees, $aNames, "compr_1");
print_r($result);
?>
Allowing me to get the "employee" that's not in the name list:
Array ( [2] => Array ( [last_name] => Flagg [first_name] => Randall [phone] => 666-1000 ) )
Something interesting to note, is that the two arguments to the compare function don't correspond to array1 and array2. That's why there has to be logic in it to handle that either of the arguments might be pointing to the more complex employee array. (Found this out the hard way.)
I think the example given here using classes is convoluting things too much to demonstrate what this function does.
array_udiff() will walk through array_values($a) and array_values($b) and compare each value by using the passed in callback function.
To put it another way, array_udiff() compares $a[0] to $b[0], $b[1], $b[2], and $b[3] using the provided callback function. If the callback returns zero for any of the comparisons then $a[0] will not be in the returned array from array_udiff(). It then compares $a[1] to $b[0], $b[1], $b[2], and $b[3]. Then, finally, $a[2] to $b[0], $b[1], $b[2], and $b[3].
For example, compare_ids($a[0], $b[0]) === -5 while compare_ids($a[1], $b[1]) === 0. Therefore, $a[1] is not returned from array_udiff() since it is present in $b.
<?
$a = array(
array(
'id' => 10,
'name' => 'John',
'color' => 'red',
),
array(
'id' => 20,
'name' => 'Elise',
'color' => 'blue',
),
array(
'id' => 30,
'name' => 'Mark',
'color' => 'red',
),
);
$b = array(
array(
'id' => 15,
'name' => 'Nancy',
'color' => 'black',
),
array(
'id' => 20,
'name' => 'Elise',
'color' => 'blue',
),
array(
'id' => 30,
'name' => 'Mark',
'color' => 'red',
),
array(
'id' => 40,
'name' => 'John',
'color' => 'orange',
),
);
function compare_ids($a, $b)
{
return ($a['id'] - $b['id']);
}
function compare_names($a, $b)
{
return strcmp($a['name'], $b['name']);
}
$ret = array_udiff($a, $b, 'compare_ids');
var_dump($ret);
$ret = array_udiff($b, $a, 'compare_ids');
var_dump($ret);
$ret = array_udiff($a, $b, 'compare_names');
var_dump($ret);
?>
Which returns the following.
In the first return we see that $b has no entry in it with an id of 10.
<?
array(1) {
[0]=>
array(3) {
["id"]=>
int(10)
["name"]=>
string(4) "John"
["color"]=>
string(3) "red"
}
}
?>
In the second return we see that $a has no entry in it with an id of 15 or 40.
<?
array(2) {
[0]=>
array(3) {
["id"]=>
int(15)
["name"]=>
string(5) "Nancy"
["color"]=>
string(5) "black"
}
[3]=>
array(3) {
["id"]=>
int(40)
["name"]=>
string(4) "John"
["color"]=>
string(6) "orange"
}
}
?>
In third return we see that all names in $a are in $b (even though the entry in $b whose name is 'John' is different, the anonymous function is only comparing names).
<?
array(0) {
}
?>
Very easy way of achieving a case-insensitive version of array_diff (or indeed array_diff_assoc, array_intersect or any of these types of functions which have a similar function that takes a callback function as one of their parameters):
array_udiff($array1, $array2, 'strcasecmp');
This works because strcasecmp() compares two strings case-insensitively, as compared to the array_diff() which compares two strings by using the == operator, which is case-sensitive.
This functionality is now implemented in the PEAR package PHP_Compat.
More information about using this function without upgrading your version of PHP can be found on the below link:
http://pear.php.net/package/PHP_Compat
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