Usage and example of PHP array_keys() function

PHP Array Function Manual

The PHP array_keys() function returns partial or all key names in the array

Syntax

array_keys( $input[, $search_value[, $strict]]);

Definition and Usage

array_keys() returns the key names of numbers or strings in the input array.
If the optional parameter search_value is specified, only the key names of that value are returned. Otherwise, all key names in the input array are returned.

Parameter

Return value

It returns keys, numbers, and strings from the $input array

Online example

<?php
　　　$input = array("a" => "Monkey", "b" => "Cat", "c" => "Dog");
　　　print_r(array_keys($input));
　　　
　　　$input = array("a" => "Monkey", "b" => "Cat", "c" => "Dog");
　　　print_r(array_keys($input, "Dog"));
　　　
　　　$input = array(10,20,30, "10");
　　　print_r(array_keys($input, "10", false));
?>

Output result:

Array
(
　　　　[0] => a
　　　　[1] => b
　　　　[2] => c
)
Array
(
　　　　[0] => c
)
Array
(
　　　　[0] => 0
　　　　[1] =>　3
)

PHP Array Function Manual