Question

This is my current array which keep a first character from the value

Array ( [n] => Array ( [0] => name_john ) [a] => Array ( [0] => age_30 ) )

foreach ($queryArray as $key) {
    $inArray[$key[0]][] = $key;
}

Question : How do I grab a word before underscore and change the array to be like

Array
(
    [name] => Array
        (
            [0] => name_john
        )

    [age] => Array
        (
            [0] => age_30
        )

)

Answer 1

To parse out the word before the underscore, use explode:

// $key = name_john
$split_key = explode('_',$key);
// $split_key[0] equals name