Regular Expression-how to write a regular expression in PHP that matches an intranet IP address ^ 192.168. [0-255] +. [0-255] $

To use a regular expression to match an IP address, write ^ 192.168. [0-255] +. [0-255] $, but it is incorrect! [] [0-9a-z] But not [0-255] Regular Expressions

Use a regular expression to match the IP address.^192\.168\.[0-255]+\.[0-255]$But it is wrong!
Regular Expression[]Not Restricted[0-9a-z]But not limited[0-255]?

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Use a regular expression to match the IP address.^192\.168\.[0-255]+\.[0-255]$But it is wrong!
Regular Expression[]Not Restricted[0-9a-z]But not limited[0-255]?

Server
filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4);

================ Edit the answer, in fact, I just wanted to introduce this function ================

function isPrivateIP($ip) {    return !filter_var($ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE);}

/*** Determine the Intranet IP ** @ param $ ip ** @ returns */public function isInternalIp ($ ip) {$ ip = ip2long ($ ip ); $ net_a = ip2long ('10. 255.255.255 ')> 24; // The Network Address of the reserved ip address of Class A network $ net_ B = ip2long ('2017. 172. 31.255.255 ')> 20; // The Network Address of the reserved ip address for the B-type network $ net_c = ip2long ('1970. 192. 168.20.255 ')> 16; // return $ ip> 24 ===$ net_a | $ ip> 20 ===$ net_ B | $ ip> 16 ===$ net_c ;}

$ Long = ip2long ($ ip) if ($ long =-1 | $ long = FALSE) {echo 'invalid IP, please try again ';} else {// if $ long is in the range you need .}

25[0-5]|2[0-4][0-9]|1[0-9]{2}|[1-9][0-9]|[0-9]

[0-9] yes, but not [0-10]. Because[]Only one of them is matched. The length can only be 1.

...... I'm curious about your application scenario.

• The IP address must be used with the subnet mask to determine whether it belongs to the same intranet.
• The IP address may be expressed as a decimal integer. If the server is installed with an http server, visit http: // 2130706433.
• IPv6 is also a problem.

Regular expressions should not be used for detailed verification of IP addresses.There are many problems to be solved using regular expressions. For example, the regular expression matches XML/JSON. I am in favor of using regular expressions to roughly find a sub-string that may be an IP address. However, for further verification of the IP address, we recommend that you refer to this topic.

For example, if only IPv4 addresses in general format are used, it is recommended that(?:(\d{1,3})\.)(\d{1,3})And then write the program to check the number of IP addresses.

^192\.168\.1?[0-9]{1,2}\.1?[0-9]{1,2}$

Could use this verification: http://jex.im/regulex! Embed = false & flags = & re = % 5E (a % 7Cb) * % 3F % 24