检查输入的用户名是否符合规定

<?php
/**
* 检测输入中是否含有错误字符
* @author ruxing.li
* @param char $string 要检查的字符串名称
* @return boolean
*/
function is_badword($string) {
$badwords = array("\\",'&',' ',"'",'"','/','*',',','<','>',"\r","\t","\n","#");
foreach($badwords as $value){
if(strpos($string, $value) !== false) {
return true;
}
}
return false;
}

/**
* 检查用户名是否符合规定
* @author ruxing.li
* @param string $username 要检查的用户名
* @return boolean
*/
function is_username($username) {
$strlen = strlen($username);
if(is_badword($username) || !preg_match("/^[a-zA-Z0-9_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]+$/", $username)){
return false;
} elseif ( 20 < $strlen || $strlen < 2 ) {
return false;
}
return true;
}

var_dump(is_username('ruxing.li')); //boolean false

var_dump(is_username('ruxingli')); //boolean true