PHP 8 reference · Array Functions

PHP in_array() Function

Check whether a value exists in an array. Pass true as the third argument for a strict (===) comparison.

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Syntax

in_array(mixed $needle, array $haystack, bool $strict = false): bool

Parameter	Description
`needle`	The value to find.
`haystack`	The array to search.
`strict` optional	`true` also checks the type (`===`). Default: `false`

true if found.

Is it in the array?Try it yourself

<?php
$roles = ["admin", "editor"];
var_dump(in_array("editor", $roles));
var_dump(in_array("guest", $roles));

Output

bool(true)
bool(false)

Use strict modeTry it yourself

<?php
var_dump(in_array("1e1", ["10"]));       // loose: both are 10
var_dump(in_array("1e1", ["10"], true)); // strict

Output

bool(true)
bool(false)

Loose comparison can match unexpected values; pass true as the third argument unless you need conversion.
For many lookups in a big list, flip it once ($set = array_flip($list)) and use isset($set[$value]).

Version	Change
PHP 4.0	Added

array_search() · Search an array for a value and return the first matching key, or false if it isn't there.
array_key_exists() · Check whether an array has a given key, even if its value is null. isset() returns false for null values.
array_any() · Return true if at least one element passes a callback test, stopping at the first match. Added in PHP 8.4.
PHP Arrays · tutorial
PHP Array Functions · tutorial

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