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# PHP array_keys() Function [Complete PHP Array Reference](#) ## Example Returns a new array containing all the keys from the input array: "XC90","BMW"=>"X5","Toyota"=>"Highlander"); print_r(array_keys($a)); ?> [Run Example »](#) * * * ## Definition and Usage The array_keys() function returns a new array containing all the keys from the input array. * * * ## Syntax array_keys(_array,value,strict_) | Parameter | Description | | :--- | :--- | | _array_ | Required. Specifies the array. | | _value_ | Optional. You can specify a value, then only the keys for that value will be returned. | | _strict_ | Optional. Used with the value parameter. Possible values: * true - Returns keys with the specified value, depending on type. Number 5 is not the same as string "5". * false - Default value. Not dependent on type. Number 5 is the same as string "5". | ## Technical Details | Return Value: | Returns a new array containing all the keys from the input array. | | :--- | | PHP Version: | 4+ | | Changelog: | The _strict_ parameter was added in PHP 5.0. | * * * ## More Examples ## Example 1 Using the value parameter: "XC90","BMW"=>"X5","Toyota"=>"Highlander"); print_r(array_keys($a,"Highlander")); ?> [Run Example »](#) ## Example 2 Using the strict parameter (false): [Run Example »](#) ## Example 3 Using the strict parameter (true): [Run Example »](#) * * Complete PHP Array Reference](#)