Given an array, I would like a flattened version of the array keys. Each array key would need the 'path' of the array, to that point, appended with an underscore.
An example explains this best.
$arr = array("location"=>0,"details"=>array("width"=>0,"height"=>0,"level"=>array("three"=>0)));
function answer($arr) {....}
the answer function would return this:
array("location","details_width","details_height","details_level_three");
UPDATE:
Here is the work in progress. It will accept an array and return the array keys, but with no depth:
function recursive_keys($input)
{
$output = array_keys($input);
foreach($input as $sub){
if(is_array($sub)){
$output = array_merge($output, recursive_keys($sub));
}
}
return $output;
}