array_search

About searcing in multi-dimentional arrays; two notes on "xfoxawy at gmail dot com";

It perfectly searches through multi-dimentional arrays combined with array_column() (min php 5.5.0) but it may not return the values you'd expect.

<?php array_search($needle, array_column($array, 'key')); ?>

Since array_column() will produce a resulting array; it won't preserve your multi-dimentional array's keys. So if you check against your keys, it will fail.

For example;

<?php
$people = array(
  2 => array(
    'name' => 'John',
    'fav_color' => 'green'
  ),
  5=> array(
    'name' => 'Samuel',
    'fav_color' => 'blue'
  )
);

$found_key = array_search('blue', array_column($people, 'fav_color'));
?>

Here, you could expect that the $found_key would be "5" but it's NOT. It will be 1. Since it's the second element of the produced array by the array_column() function.

Secondly, if your array is big, I would recommend you to first assign a new variable so that it wouldn't call array_column() for each element it searches. For a better performance, you could do;

<?php
$colors = array_column($people, 'fav_color');
$found_key = array_search('blue', $colors);
?>

If you are using the result of array_search in a condition statement, make sure you use the === operator instead of == to test whether or not it found a match.  Otherwise, searching through an array with numeric indicies will result in index 0 always getting evaluated as false/null.  This nuance cost me a lot of time and sanity, so I hope this helps someone.  In case you don't know what I'm talking about, here's an example:

<?php
$code = array("a", "b", "a", "c", "a", "b", "b"); // infamous abacabb mortal kombat code :-P

// this is WRONG
while (($key = array_search("a", $code)) != NULL)
{
 // infinite loop, regardless of the unset
 unset($code[$key]);
}

// this is _RIGHT_
while (($key = array_search("a", $code)) !== NULL)
{
 // loop will terminate
 unset($code[$key]);
}
?>

for searching case insensitive better this:

<?php
array_search(strtolower($element),array_map('strtolower',$array));
?>

Despite PHP's amazing assortment of array functions and juggling maneuvers, I found myself needing a way to get the FULL array key mapping to a specific value. This function does that, and returns an array of the appropriate keys to get to said (first) value occurrence.

function array_recursive_search_key_map($needle, $haystack) {
    foreach($haystack as $first_level_key=>$value) {
        if ($needle === $value) {
            return array($first_level_key);
        } elseif (is_array($value)) {
            $callback = array_recursive_search_key_map($needle, $value);
            if ($callback) {
                return array_merge(array($first_level_key), $callback);
            }
        }
    }
    return false;
}

usage example:
-------------------

$nested_array = $sample_array = array(
    'a' => array(
        'one' => array ('aaa' => 'apple', 'bbb' => 'berry', 'ccc' => 'cantalope'),
        'two' => array ('ddd' => 'dog', 'eee' => 'elephant', 'fff' => 'fox')
    ),
    'b' => array(
        'three' => array ('ggg' => 'glad', 'hhh' => 'happy', 'iii' => 'insane'),
        'four' => array ('jjj' => 'jim', 'kkk' => 'kim', 'lll' => 'liam')
    ),
    'c' => array(
        'five' => array ('mmm' => 'mow', 'nnn' => 'no', 'ooo' => 'ohh'),
        'six' => array ('ppp' => 'pidgeon', 'qqq' => 'quail', 'rrr' => 'rooster')
    )
);

$search_value = 'insane';

$array_keymap = array_recursive_search_key_map($search_value, $nested_array);

var_dump($array_keymap);
// Outputs:
// array(3) {
// [0]=>
//  string(1) "b"
//  [1]=>
//  string(5) "three"
//  [2]=>
//  string(3) "iii"
//}

----------------------------------------------

But again, with the above solution, PHP again falls short on how to dynamically access a specific element's value within the nested array. For that, I wrote a 2nd function to pull the value that was mapped above.

function array_get_nested_value($keymap, $array)
{
    $nest_depth = sizeof($keymap);
    $value = $array;
    for ($i = 0; $i < $nest_depth; $i++) {
        $value = $value[$keymap[$i]];
    }

    return $value;
}

usage example:
-------------------
echo array_get_nested_value($array_keymap, $nested_array);   // insane

Be careful!

<?php

var_dump(array_search('needle', [ 0 => 0 ])); // int(0) (!)

var_dump(array_search('needle', [ 0 => 0 ], true)); // bool(false)

?>

But, in php 8

<?php

var_dump(array_search('needle', [ 0 => 0 ])); // bool(false)

?>

To expand on previous comments, here are some examples of
where using array_search within an IF statement can go
wrong when you want to use the array key thats returned.

Take the following two arrays you wish to search:

<?php
$fruit_array = array("apple", "pear", "orange");
$fruit_array = array("a" => "apple", "b" => "pear", "c" => "orange");

if ($i = array_search("apple", $fruit_array))
//PROBLEM: the first array returns a key of 0 and IF treats it as FALSE

if (is_numeric($i = array_search("apple", $fruit_array)))
//PROBLEM: works on numeric keys of the first array but fails on the second

if ($i = is_numeric(array_search("apple", $fruit_array)))
//PROBLEM: using the above in the wrong order causes $i to always equal 1

if ($i = array_search("apple", $fruit_array) !== FALSE)
//PROBLEM: explicit with no extra brackets causes $i to always equal 1

if (($i = array_search("apple", $fruit_array)) !== FALSE)
//YES: works on both arrays returning their keys
?>

FYI, remember that strict mode is something that might save you hours.

If you're searching for a string and you have a "true" boolean on the way - you will get it as result (first occurrence). Example below:

<?php

$arr = [
    'foo'    => 'bar',
    'abc'    => 'def',
    'bool'   => true,
    'target' => 'xyz'
];

var_dump( array_search( 'xyz', $arr ) ); //bool
var_dump( array_search( 'xyz', $arr, true ) ); //target

?>

Expanding on the comment by hansen{}cointel.de:

When searching for a string and the array contains 0 (zero), the string is casted to (int) by the type-casting which is always 0 (perhaps the opposite is the proper behaviour, the array value 0 should have been casted to string). That produces unexpected results if strict comparison is not used:

<?php
$a = array(0, "str1", "str2", "str3");
echo "
str1 = ".array_search("str1", $a).",
str2 = ".array_search("str2", $a).",
str3 = ".array_search("str3", $a).",

str1 strict = ".array_search("str1", $a, true).",
str2 strict = ".array_search("str2", $a, true).",
str3 strict = ".array_search("str3", $a, true);
?>

This will return:
str1 = 0, str2 = 0, str3 = 0, str1 strict = 1, str2 strict = 2, str3 strict = 3

Combining syntax of array_search() and functionality of array_keys() to get all key=>value associations of an array with the given search-value:
<?php
function array_search_values