PHP Manual: Checks if a value exists in an array

Description

bool in_array ( mixed $needle , array $haystack [, bool $strict = FALSE ] )

Searches haystack for needle using loose comparison unless strict is set.

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 in_array function will also check the types of the needle in the haystack.

Return Values

Returns TRUE if needle is found in the array, FALSE otherwise.

Changelog

Version	Description
4.2.0	`needle` may now be an array.

Examples

Example #1 in_array example


<?php
$os = array("Mac", "NT", "Irix", "Linux");
if (in_array("Irix", $os)) {
    echo "Got Irix";
}
if (in_array("mac", $os)) {
    echo "Got mac";
}
?>

The second condition fails because in_array is case-sensitive, so the program above will display:

Got Irix

Example #2 in_array with strict example


<?php
$a = array('1.10', 12.4, 1.13);

if (in_array('12.4', $a, true)) {
    echo "'12.4' found with strict check\n";
}

if (in_array(1.13, $a, true)) {
    echo "1.13 found with strict check\n";
}
?>

The above example will output:

1.13 found with strict check

Example #3 in_array with an array as needle


<?php
$a = array(array('p', 'h'), array('p', 'r'), 'o');

if (in_array(array('p', 'h'), $a)) {
    echo "'ph' was found\n";
}

if (in_array(array('f', 'i'), $a)) {
    echo "'fi' was found\n";
}

if (in_array('o', $a)) {
    echo "'o' was found\n";
}
?>