php如何判断IP为有效IP地址

//1、判断是否是合法IP
if(filter_var($ip, FILTER_VALIDATE_IP)) {
// it's valid
}else {
// it's not valid
}
//2、判断是否是合法的IPv4 IP地址
if(filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4)) {
// it's valid
}else {
// it's not valid
}
//3、判断是否是合法的公共IPv4地址，192.168.1.1这类的私有IP地址将会排除在外
if(filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4 | FILTER_FLAG_NO_PRIV_RANGE)) {
// it's valid
}else {
// it's not valid
}
//4、判断是否是合法的IPv6地址
if(filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_RES_RANGE)) {
// it's valid
}else {
// it's not valid
}
//5、判断是否是public IPv4 IP或者是合法的Public IPv6 IP地址
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
}