PHP array_keys() function

Example

Return a new array containing all keys in the array:

<?php$a=array("Volvo"=>"XC90","BMW"=>"X5","Toyota"=>"Highlander");print_r(array_keys($a));?>

Definition and usage

The array_keys() function returns a new array containing all the keys in the array.

grammar

 array_keys( array,value,strict )

parameter	describe
array	Required. Specifies an array.
value	Optional. You can specify a key value, and then only the key name corresponding to that key value will be returned.
strict	Optional. Used with the value parameter. Possible values: true - Returns the key name with the specified key value. Depending on the type, the number 5 is different from the string "5". false - the default value. Independent of type, the number 5 is the same as the string "5".

technical details

Return value:	Returns a new array containing all keys in the array.
PHP version:	4+
Update log:	The strict parameter is new in PHP 5.0.

More examples

Example 1

Use the value parameter:

<?php$a=array("Volvo"=>"XC90","BMW"=>"X5","Toyota"=>"Highlander");print_r(array_keys($a,"Highlander"));? >

Example 2

Use strict parameter (false):

<?php$a=array(10,20,30,"10");print_r(array_keys($a,"10",false));?>

Example 3

Use strict parameter (true):

<?php$a=array(10,20,30,"10");print_r(array_keys($a,"10",true));?>