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Arrays
* array
* array_count_values
* array_diff
* array_flip
* array_intersect
* array_keys
* array_merge
* array_merge_recursive
* array_multisort
* array_pad
* array_pop
* array_push
* array_rand
* array_reverse
* array_shift
* array_slice
* array_splice
* array_unique
* array_unshift
* array_values
* array_walk
* arsort
* asort
* compact
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* uksort
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Manual: array_diff
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Sun, 21 Jan 2001
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array_diff

(PHP 4 >= 4.0.1)

array_diff — Computes the difference of arrays

Description

array array_diff (array array1, array array2 [, array ...])

Array_diff() returns an array containing all the values of array1 that are not present in any of the other arguments. Note that keys are preserved.

Example 1. Array_diff() example


$array1 = array ("a" => "green", "red", "blue");
$array2 = array ("b" => "green", "yellow", "red");
$result = array_diff ($array1, $array2);

This makes $result have array ("blue");

See also array_intersect().


User Contributed Notes: array_diff

ks@ksweb.de
30-Aug-2000 04:44
'preserved' means the keys are taken from the first accurence of the elements.
The example is wrong:
$array1 = array ("a" => "green", "red", "blue");
$array2 = array ("b" => "green", "yellow", "red");
$result = array_diff ($array1, $array2);
print_r($result);
$your_result=array("blue");
print_r($your_result);

outputs:
Array ( [1] => blue ) Array ( [0] => blue )

the correct Array-Statement of $result is:
$result=array("","blue");

venaas@php.net
22-Oct-2000 06:30
$result will be array(1 => "blue").
There is only one element.

jzago@ifhamy.insa-lyon.fr
10-Nov-2000 10:05
--- code ---
print_r ($valeurs);
print_r ($dummy);
print_r (array_diff ($valeurs, $dummy));

--- output ---
Array ( [19] => 1 )
Array ( [0] => 1 )
Array ( )

Remember folks, it diffs the values, not the keys !

umer@ezboard.com
29-Nov-2000 08:16
when you are comparing

array1 = array ("blue", "red", "green", "yellow");

array2 = array ("blue", "orange", "white", "yellow", "black");

$result = array_diff($array2, $array1);

you get back

$result[0] = "";
$result[1] = "orange";
$result[2] = "white";
$result[3] = "";
$result[4] = "black";

odd huh.. and if you are depending on seeing if you got any thing back from both arrays.. then the best thing to do is to count($result); and go from there..

jllamas@bal.com.mx
15-Dec-2000 11:17
To umer@ezboard.com, the same problem ocurrs with array_unique. Try this solution provided by matthew_dean@hotmail.com. Use

array_values(array_unique($myArray));

or you can also use the one suggested by burno@33-24-36.com (I haven't tested it myself).

usort($myArray,"return -1");

I think this problem is present on all array functions, but will only be noticed with numerically indexed arrays.

 About Notes

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