IP conversion to number, regular matching IP

storage space Comparison:

VARCHAR type storage 0.0.0.0-255.255.255.255 is 7-15 bytes
int     Type storage is 4 bytes  1 bytes 8 bits  2^31-1  
IPv4 Essence is a 32-bit binary string   can be stored with int 

The IPv4 address (10-in-4) is converted to a 32-bit 2-in-system.

1. Convert to 2 first, then connect
 2. Left 3*8 2*8 1*8 0 Bits 

Conversion:

Conversion Mode	PHP built-in Functions	Mysql Built-in Functions
string int	PHP Long2ip (118.190.3.21)	MySQL Inet_ntoa (str_to_int)
int spin String	PHP Ip2long (3031005402)	MySQL Inet_aton (int_to_str)

function Ipton ($ip) {$ip _arr=explode ('. ', $ip);//Separate IP segment foreach ($ip _arr as $value) {$iphex =dechex ($va Lue)//convert each segment of IP to 16 if (strlen ($iphex) <2)//255 16 is FF, so the 16 feed length of each IP segment will not exceed 2 {$iphex = ' 0 '. $ip hex;//if the converted 16-digit length is less than 2, precede it with a 0//no length of 2, and the first digit is 0 of the 16-in notation, which is to handle the $ipstr when converting the number to IP. = $iphex;//Four segment IP The 16 binary number is connected to get a 16 binary string, the length is 8} return Hexdec ($IPSTR),//Convert the 16 string to 10, get the digital representation of the IP//convert the number to IP, and perform the reverse process of the above function functio
    n Ntoip ($n) {$iphex =dechex ($n);//convert 10 to 16 $len =strlen ($iphex);//Get 16 string length if (strlen ($iphex) <8) {$iphex = ' 0 '. $iphex;//If the length is less than 8, add 0 $len =strlen ($iphex) at the front;//re-get the length of the 16 feed string}//This is because the Ipton function gets the 16 in String, if the first digit is 0, after converting to a number, is not displayed//So, if the length is less than 8, must be the first bit of 0 plus go//Why must be the first 0 it, because in the Ipton function, the next paragraph plus the ' 0 ' in the middle, converted to a number, will not disappear for
    ($i =0, $j =0 $j < $len; $i = $i +1, $j = $j +2) {//loop-intercept 16-in-string, 2-length $ippart =substr ($iphex, $j, 2) per intercept, and the 16-digit number corresponding to each IP segment $fipart =substr ($ippart,0,1)//intercept the first if ($fipart = = ' 0 ') of the 16-digit number {//If the first digit is 0, the original number is only 1 digits $ippart =substr ($ippart, 1, 1);/0

    Intercept the} $ip []=hexdec ($ippart);//convert each paragraph 16 to the corresponding 10 number, that is, the value of each segment of IP} $ip = Array_reverse ($IP);
 Return implode ('. ', $ip);//Connect each segment, returning the original IP value}

Conversion principle:

1. After the string to int     Dechex segment    Max converted to 16 is FF so no more than 2  do length judgment if less than 2 0, spell the 8 in length 16, Hexdec 16 to 10 
. int spin string     inverse procedure

Regular match:

Functionis_ip ($gonten) {  
 $gonten = ' 255.190.3.21 ';

$ip =explode ('. ', $gonten);
For ($i =0 $i <count ($IP); $i + +)
{
    if ($ip [$i]>255) {return
        (0);
    }
}
Preg_match ("/^ (1?\d{1,2}) | ( 2[0-4]\D) | (25[0-5]) \.) {3} ((1?\d{1,2}) | (2[0-4]\d) | (25[0-5]) $/", $gonten);
Var_dump ($gonten);