Another array question

[sitehatchery]

Is there a way to extract a portion of an array that only contains certain values, without having to loop through the entire thing?

For instance, if I have an array that looks like this:

$arr[]=array('a', 'w');
$arr[]=array('b', 'w');
$arr[]=array('c', 'x');
$arr[]=array('d', 'y');
$arr[]=array('e', 'w');

I want to extract an array that looks like this:

$arr2[]=array('a', 'w');
$arr2[]=array('b', 'w');
$arr2[]=array('e', 'w');

effectively, limiting the second array to records that have 'w' in the second index.

It's much like using a where statement in a sql query.

Any idea how to do this without having to loop through foreach?

[NogDog]

Untested:

$arr2 = array_filter($arr, create_function('$a', 'return($a[1]=="w");')); 

[andre4s_y]

tested :

<?php
$arr[]=array('a', 'w');
$arr[]=array('b', 'w');
$arr[]=array('c', 'x');
$arr[]=array('d', 'y');
$arr[]=array('e', 'w');
function tester($n)
{
    if($n[1]=='w')
    {
        return $n;
    }
}
$arr2 = array_filter($arr,"tester");
//$arr2 = array_filter($arr, create_function('$a', 'return($a[1]=="w");')); -> same output
//if you care about index
sort($arr2);
print_r($arr2);
?>

It will output :

Array ( [0] => Array ( [0] => a [1] => w ) [1] => Array ( [0] => b [1] => w ) [2] => Array ( [0] => e [1] => w ) )

[sitehatchery]

NogDog, Thank you!

$arr2 = array_filter($arr, create_function('$a', 'return($a[1]=="w");'));

is exactly what I needed! You did say it was untested, but I should add–for others searching for a similar answer–that the first parameter, '$a', only works without the single quotes.

andre4s_y, thank you as well for:

$arr2 = array_filter($arr,"tester");

The way you broke it down with the separate callback function helped me understand how the array_filter function worked. However, since I'm using it within a class, I couldn't figure out how to use the callback function within the class. For instance:

$arr2 = array_filter($arr, $this->"tester");
or
$arr2 = array_filter($arr, "$this->tester");

didn't work. This is an issue that I've had with callback functions before. Do you (or anyone else) know how to use this inside of a class?

[Znupi]

I couldn't figure out how to use the callback function within the class.

http://php.net/callback
Basically: array_filter($arr, Array($this, "tester")); or: array_filter($arr, Array("ClassName", "tester"));

[sitehatchery]

Aha! THanks, In the past, I've looked for it on PHP.net, did google searches and have even posted threads here on that. Don't know why I always came up short of the answer. Thanks for your response!

[sitehatchery]

Well, NogDog... you were right. You do need the single quotes around the $a. When I didn't include it, I mistakenly thought it worked because it returned all rows.

[NogDog]

Well, NogDog... you were right....

Was there ever any doubt?