PHP Manual: Checks if a value exists in an array

Description

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

Searches for needle in haystack 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.

Note:
Prior to PHP 8.0.0, a string needle will match an array value of 0 in non-strict mode, and vice versa. That may lead to undesireable results. Similar edge cases exist for other types, as well. If not absolutely certain of the types of values involved, always use the strict flag to avoid unexpected behavior.

Return Values

Returns true if needle is found in the array, false otherwise.

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";
}
?>

The above example will output:

'ph' was found
'o' was found

in_array

Description

Parameters

Return Values

Examples

See Also