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(PHP 4 >= 4.0.1) array_diff -- Computes the difference of arrays Descriptionarray 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.
Esempio 1. Array_diff() example
$array1 = array ("a" => "green", "red", "blue");
$array2 = array ("b" => "green", "yellow", "red");
$result = array_diff ($array1, $array2);
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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");
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venaas@php.net
22-Oct-2000 06:30 |
$result will be array(1 => "blue").
There is only one element.
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jzago@ifhamy.insa-lyon.fr
10-Nov-2000 10:05 |
--- code ---
print_r ($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 !
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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..
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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.
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php-general@lists.php.net
06-Apr-2001 12:58 |
SHEESH! Ok after about an hour and a half of looking at print_r() output and rewriting my own code, I figured it out - numeric indexes are "keys" too... meaning:
---CODE---
$blah = array("eat","my","shorts");
$fooey = array("my","shorts","eat","you");
$yay = array_diff($fooey,$blah);
print_r($yay);
---OUTPUT---
array [
[3] => "you"
]
This causes for() loops to produce unexpected results:
for ($i=0; $i!=count($yay); $i++)
{
// do something with $yay[$i];
}
This stinks IMO - even though in much of PHP's functionality, the cross-functionality between numeric and associative arrays is all good, this is kind of silly... maybe a third option is in order, NUM_INDEX or something?
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nhawks@intercosmos.com
06-Apr-2001 01:05 |
Here's how I worked around my prior problem about array_diff() and numeric indexes being turned associative.
if (is_array($yay))
{
$yay = array_values($yay);
}
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david@audiogalaxy.com
08-Apr-2001 04:12 |
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Note that array_diff() considers the type of the array elements when it compares them. If array_diff() doesn't appear to be working, check your inputs using var_dump() to make sure you're not trying to diff an array of integers with an array of strings.
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array_count_values