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Digg  array_udiff
Computes the difference of arrays by using a callback function for data comparison
(PHP 5)
Example 282. array_udiff() example<?phpThe above example will output: ArrayCode Examples / Notes » array_udiffdmhouse
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, $array2, 'strcasecmp'); This works because strcasecmp() compares two strings case-insensitively, as compared to the array_diff() which compares two strings by using the == operator, which is case-sensitive. aidan
This functionality is now implemented in the PEAR package PHP_Compat. More information about using this function without upgrading your version of PHP can be found on the below link: http://pear.php.net/package/PHP_Compat colin
I think the example given here using classes is convoluting things too much to demonstrate what this function does. array_udiff() will walk through array_values($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) { } ?> |
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