Using if and elseif to check post input

i want to check my post input is it have a right character length, is it contains only character, or is it empty. but it seem i doing it in correctly, can anyone tell me which is caused error in my code? here's my code that i use to validate my name field:

if (empty($_POST['name'])){
        $errors[] = "your name can't be empty";}
    } elseif (strlen($_POST['name'] < 6|)){
        $errors[] = 'your name must have lengh at least 6 character.<br/>';
    } elseif (strlen($_POST['name']) > 31|){
        $errors[] = 'your name is suppose below 30 character".<br/>';
    }else if (!ctype_alpha($_POST['name'])) {
        $errors[] = "Please enter only a character.";
    }

is it the right way to check my input or is it any a better way in doing this?