array_keys

The array_keys() function in PHP takes an array as it’s argument and returns all the keys in that array (as a numeric array).

PHP

$array = array('go' => 'green', 'stop' => 'red');
var_dump( array_keys($array) );
/*
Array (
	[0] => go
	[1] => stop
)
*/

To replicate this functionality in Ruby, we need to use a Hash object, since arrays in Ruby don’t use associative key/value pairs.

Ruby

array = { :go => 'green', :stop => 'red' };
puts array.keys;
# => [:go, :stop]