将表单输入组合成1行

i want to combine fname and lname into a one input

$fname = trim($_POST['fname']);
$lname = trim($_POST['lname']);

and i want input this result into my sql table

 function random_username( $length = 4 ) {
    $chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
    $password = substr( str_shuffle( $chars ), 0, $length );
    return $usercode;
} 

how about that combining code?

NOTE: *Sorry for my bad english

Hi if you want to concate firstname and lastname then simply use concatnation

$fname = trim($_POST['fname']);
$lname = trim($_POST['lname']);

$userfullname = $fname." ".$lname; // this will give use your fullname