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Array Functions
PHP Manual

# array_search

(PHP 4 >= 4.0.5, PHP 5)

array_search — Searches the array for a given value and returns the corresponding key if successful

### Description

mixed array_search ( mixed `$needle` , array `$haystack` [, bool `$strict` = false ] )

Searches `haystack` for `needle`.

### Parameters

`needle`

  The searched value.

  > Note:

  > If `needle` is a string, the comparison is done in a case-sensitive manner.

`haystack`

  The array.

`strict`

  If the third parameter `strict` is set to `TRUE` then the array_search() function will search for identical elements in the `haystack`. This means it will also check the types of the `needle` in the `haystack`, and objects must be the same instance.

### Return Values

Returns the key for `needle` if it is found in the array, `FALSE` otherwise.

If `needle` is found in `haystack` more than once, the first matching key is returned. To return the keys for all matching values, use array_keys() with the optional `search_value` parameter instead.

Warning

This function may return Boolean `FALSE`, but may also return a non-Boolean value which evaluates to `FALSE`. Please read the section on Booleans for more information. Use the === operator for testing the return value of this function.

### Changelog

Version | Description
--- | ---
5.3.0 | As with all internal PHP functions as of 5.3.0, array_search() returns `NULL` if invalid parameters are passed to it.
4.2.0 | Prior to PHP 4.2.0, array_search() returns `NULL` on failure instead of `FALSE`.

### Examples

Example #1 array_search() example

`<?php
$array = array(0 => 'blue', 1 => 'red', 2 => 'green', 3 => 'red');
$key = array_search('green', $array); // $key = 2;
$key = array_search('red', $array); // $key = 1;
?>`

### See Also

- array_keys() - Return all the keys or a subset of the keys of an array
- array_values() - Return all the values of an array
- array_key_exists() - Checks if the given key or index exists in the array
- in_array() - Checks if a value exists in an array

array_reverse
array_shift
Array Functions
PHP Manual