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Text lesson

array_keys()

Example

The array_keys() function returns an array containing the keys of a given array.

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

Definition and Usage

The array_keys() function returns an array of the keys.

Syntax

array_keys(array, value, strict)

Parameter Values

Parameter	Description
array	Required. Specifies the array.
value	Optional. If a value is specified, only the keys corresponding to that value are returned.
strict	Optional. Used with the value parameter. Possible values: true – Returns the keys with the specified value, considering type (e.g., the number 5 is not the same as the string “5”). false – Default value. Does not consider type (e.g., the number 5 is considered the same as the string “5”).

Technical Details

Return Value:	Returns an array of the keys.
PHP Version:	4+
Changelog:	The strict parameter was introduced in PHP 5.0.

More Examples

Example

When using the value parameter:

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

Example

When using the strict parameter set to false:

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

Example

When using the strict parameter set to true:

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