http://goo.gl/vKd6Co

<?

    // Separate input generator
    function genSeparateInput($name,$size){
        $c = "";
        for($i=0; $i < $size; $i++){
            $c .= "<input name='".$name."[]' maxlength='1' size='1' />";
        }
        return $c;
    }

    // Format separate input
    function getSeparateData($input_array,$name_array){
        $array = array();
        // loop each separate input
        foreach($name_array as $name){
            //if inputbox is null , insert space
            for($i = 0;$i < sizeof($input_array[$name]);$i++)
                if(strlen($input_array[$name][$i]) == 0)
                    $input_array[$name][$i] = " ";

            $array[$name] = trim(implode("",$input_array[$name]));
        }
        return $array;
    }


    if($_POST){
        $separate_array = array("first_name","last_name");
        $formated_data = getSeparateData($_POST,$separate_array);

        //Print result
        echo "<pre>" . print_r($formated_data) . "</pre>";
    }


?>

<form method="POST" action="test.php">
    First Name:<?=genSeparateInput("first_name",10);?><br/>
    Last Name:<?=genSeparateInput("last_name",12);?><br/>
    <input type="submit"/>
</form>