PHP get array key

In this post, you will learn how to get array key in PHP programming language.

An array is a collection of key/value pairs. We can store more than one item in only one variable, i.e., Array. So Array is used when there is a requirement to add more items in a single variable. To create an array, we are using an array() construct. Each element in an array is separated by a comma.

In development process, sometime we require to get the array keys. There are many processes to get the array keys. But the simplest way is by using the PHP inbuilt function array_keys().

Syntax

array_keys(array, value, strict)

Here, the array is the required parameter. It specifies an array. The value is optional parameter. If specified, then only keys containing these values are returned. The strict is also an optional parameter. This parameter was added in PHP 5.0. It is used with the value parameter. The possible values are -

• true : It returns the keys with the specified value, depending on the type.
• false : It is default value.

This function returns an array of all the keys in array.

PHP example to get array key

Here is the following simple example to get the array key -

<?php
$arr1 = array(1 => 100, "color" => "green", "width" => 220);
print_r(array_keys($arr1));

$arr2 = array("apple", "orange", "banana", "kiwi", "lemon");
print_r(array_keys($arr2));
?>

Array ( [0] => 1 [1] => color [2] => width ) 
Array ( [0] => 0 [1] => 1 [2] => 2 [3] => 3 [4] => 4 )

PHP example to get array key

<?php
$array = array("apple", "orange", "banana", "kiwi", "lemon");
print_r(array_keys($array,"kiwi"));
?>

Array ( [0] => 3 )

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