ip2long IP地址转换成整型。

long2ip 整型数据转换成IP。

子网掩码转换成掩码长度方式：

$slash_notation = strlen(preg_replace("/0/", "", decbin(ip2long($subnet_mask))));$bits=strpos(decbin(ip2long($mask)),"0");

子网掩码位长转换成子网掩码形式：

$mask = 0xffffffff << (32 - $mask);$mask = pow(2,32)-pow(2,(32-$mask));

判断两个地址是否在一个子网内：

<?phpfunction matchCIDR($addr, $cidr) {    list($ip, $mask) = explode('/', $cidr);   return (ip2long($addr) >> (32 - $mask) == ip2long($ip) >> (32 - mask));}?>

一个IPv4的类：

<?php

 //--------------

// IPv4 classclass ipv4{   var $address;  var $netbits;

   //--------------

  // Create new class  function ipv4($address,$netbits)  {     $this->address = $address;    $this->netbits = $netbits;  }

   //--------------

  // Return the IP address  function address() { return ($this->address); }

   //--------------

  // Return the netbits  function netbits() { return ($this->netbits); }

   //--------------

  // Return the netmask  function netmask()  {     return (long2ip(ip2long("255.255.255.255")           << (32-$this->netbits)));  }

   //--------------

  // Return the network that the address sits in  function network()  {     return (long2ip((ip2long($this->address))           & (ip2long($this->netmask()))));  }

   //--------------

  // Return the broadcast that the address sits in  function broadcast()  {     return (long2ip(ip2long($this->network())           | (~(ip2long($this->netmask())))));  }

   //--------------

  // Return the inverse mask of the netmask  function inverse()  {     return (long2ip(~(ip2long("255.255.255.255")           << (32-$this->netbits))));  }

}

  $ip = new ipv4("192.168.2.1",24);

  print "Address: $ip->address()\n";  print "Netbits: $ip->netbits()\n";  print "Netmask: $ip->netmask()\n";  print "Inverse: $ip->inverse()\n";  print "Network: $ip->network()\n";  print "Broadcast: $ip->broadcast()\n";?>

这个做法比较有创意：

For those poor little people using PHP 3, here's an ip2long:<?phpif (!function_exists("ip2long")) {  function ip2long($ip) {   $ex = explode(".", $ip);  if (count($ex)!=4) return -1;  list($a, $b, $c, $d) = $ex;  $a = $a*16777216;  $b = $b*65536;  $c = $c*256;  return $a+$b+$c+$d; }}?>

#!/usr/local/bin/php

<?   $ip_addr = "172.14.1.57";   $subnet_mask = "255.255.255.0";

   $ip = ip2long($ip_addr);

   $nm = ip2long($subnet_mask);   $nw = ($ip & $nm);   $bc = $nw | (~$nm);

   echo "IP Address:         " . long2ip($ip) . "\n";

   echo "Subnet Mask:        " . long2ip($nm) . "\n";   echo "Network Address:    " . long2ip($nw) . "\n";   echo "Broadcast Address:  " . long2ip($bc) . "\n";   echo "Number of Hosts:    " . ($bc - $nw - 1) . "\n";   echo "Host Range:         " . long2ip($nw + 1) . " -> " . long2ip($bc - 1)  . "\n";?>

Produces the output:

IP Address:         172.14.1.57

Subnet Mask:        255.255.255.0Network Address:    172.14.1.0Broadcast Address:  172.14.1.255Number of Hosts:    254Host Range:         172.14.1.1 -> 172.14.1.254