PHP array_keys() Function

PHP Array Functions

Example

Returns a new array containing all the keys of the array:

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

Run Instances

Definition and Usage

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

If the second parameter is provided, only the key names with the specified key value will be returned.

If strict If the parameter is specified as true, PHP will use an identity comparison (===) to strictly check the data type of the key value.

Syntax

array_keys(array,value,strict)
Parameters Description
array Required. Specifies the array.
value Optional. You can specify a key value, and only the key names corresponding to that key value will be returned.
strict

Optional. With value Parameters used together. Possible values:

  • true - Returns the keys with the specified key value. Dependent on type, the number 5 is different from the string "5".
  • false - Default value. Does not depend on type, the number 5 is the same as the string "5".

Technical Details

Return Value: Returns a new array containing all the keys of the array.
PHP Version: 4+
Update Log: strict The parameter was added in PHP 5.0.

More Examples

Example 1

Use value parameter:

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

Run Instances

Example 2

Use strict parameter (false):

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

Run Instances

Example 3

Use strict parameter (true):

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

Run Instances

PHP Array Functions