Write a PHP program to create a letter range with arbitrary length

<?php
function letter_range($length)
{
    $data_range = array();
    $letters = range('A', 'Z');
    for($i=0; $i<$length; $i++)
    {
        $position = $i*26;
        foreach($letters as $ii => $letter)
        {
            $position++;
            if($position <= $length)
                $data_range[] = ($position > 26 ? $data_range[$i-1] : '').$letter;
        }
    }
    return $data_range;
}
print_r(letter_range(7));
?>

Sample Output:

Array                                                       
(                                                           
    [0] => A                                                
    [1] => B                                                
    [2] => C                                                
    [3] => D                                                
    [4] => E                                                
    [5] => F                                                
    [6] => G                                                
)