php使用preg_match()函数验证ip地址的方法

preg_match('/^(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:[.](?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}$/', $ipAddress);

<?php
/*
*@return Boolen
*@param String $ip 要匹配的ip地址
*@param String $pat 匹配的正则规则
*@param Boolen 匹配成功后返回的布尔值
*preg_match()
*0为不成功，1为成功
*/
function fun($ip){
  //0.0.0.0--- 255.255.255.255
  $pat = "/^(((1?\d{1,2})|(2[0-4]\d)|(25[0-5]))\.){3}((1?\d{1,2})|(2[0-4]\d)|(25[0-5]))$/";
  if(preg_match($pat,$ip)){
   $num = preg_match($pat,$ip);
   return $num;
  }else{
   $num = preg_match($pat,$ip);
   return $num;
  }
}
echo fun("255.255.255.255");

if(filter_var($ip, FILTER_VALIDATE_IP)) {
// it's valid
}
else {
// it's not valid
}

if(filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4)) {
// it's valid
}
else {
// it's not valid
}

if(filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4 | FILTER_FLAG_NO_PRIV_RANGE)) {
// it's valid
}
else {
// it's not valid
}

if(filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_RES_RANGE)) {
// it's valid
}
else {
// it's not valid
}

if(filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE)) {
// it's valid
}
else {
// it's not valid
}