PHP显示错误消息并重新显示正确的字段。

I have an email form that checks three fields, name, valid email and comments. But the way it's set up now, since name and comments are in one function it first checks name and comments even if email is not valid, how can I re-write it so it checks the fields in order. Also, I would like to re-display the fields that have no errors, so the user doesn't have to type again. Please help. ThanksI have an email form that checks three fields,