求个正则表达式

Question

<?php
Function Check_User_Name($rwName){
$Che = preg_match ("/^[[:alpha:][:digit:]]+[[:alpha:]_]+[[:alpha:][:digit:]_]*/i",$rwName);
if (strlen($rwName)>=4 && strlen($rwName)<=16 && $Che == 1){
printf ('%s<br />',$rwName) ;
}else{
printf ('%s<br />','False!') ;
}
}
Check_User_Name('8888888');
Check_User_Name('88a');
Check_User_Name('8888888888888888888888888888888');
Check_User_Name('MoXie');
Check_User_Name('SysTem128');
Check_User_Name('Shinson_Moon');
?>为什么重复发帖？

Answer 1

echo (preg_match("/^[0-9[:alpha:]][0-9[:alpha:]]{2,4}$/", $username) && !is_numeric($username)) ? "Y" : "N";

Answer 2

错了，改一下echo (preg_match("/^[0-9[:alpha:]][0-9[:alpha:]]{3,15}$/", $username) && !is_numeric($username)) ? "Y" : "N";

Answer 3

错了，改一下echo (preg_match("/^[0-9[:alpha:]][0-9[:alpha:]_\-]{3,15}$/", $username) && !is_numeric($username)) ? "Y" : "N";