(PHP 4, PHP 5)
ip2long — Converts a string containing an (IPv4) Internet Protocol dotted address into a long integer
$ip_address
   )The function ip2long() generates an long integer representation of IPv4 Internet network address from its Internet standard format (dotted string) representation.
ip2long() will also work with non-complete IP addresses. Read » http://publibn.boulder.ibm.com/doc_link/en_US/a_doc_lib/libs/commtrf2/inet_addr.htm for more info.
ip_addressA standard format address.
   Returns the long integer or FALSE if ip_address
   is invalid.
  
| Version | Description | 
|---|---|
| 5.5.0 | Prior to this version, on Windows ip2long() would sometimes return a valid number even if passed a value which was not an (IPv4) Internet Protocol dotted address. | 
| 5.2.10 | Prior to this version, ip2long() would sometimes return a valid number even if passed a value which was not an (IPv4) Internet Protocol dotted address. | 
Example #1 ip2long() Example
<?php
$ip = gethostbyname('www.example.com');
$out = "The following URLs are equivalent:<br />\n";
$out .= 'http://www.example.com/, http://' . $ip . '/, and http://' . sprintf("%u", ip2long($ip)) . "/<br />\n";
echo $out;
?>
Example #2 Displaying an IP address
This second example shows how to print a converted address with the printf() function in both PHP 4 and PHP 5:
<?php
$ip   = gethostbyname('www.example.com');
$long = ip2long($ip);
if ($long == -1 || $long === FALSE) {
    echo 'Invalid IP, please try again';
} else {
    echo $ip   . "\n";           // 192.0.34.166
    echo $long . "\n";           // -1073732954
    printf("%u\n", ip2long($ip)); // 3221234342
}
?>
Note:
Because PHP's integer type is signed, and many IP addresses will result in negative integers on 32-bit architectures, you need to use the "%u" formatter of sprintf() or printf() to get the string representation of the unsigned IP address.
Note:
ip2long() will return
FALSEfor the IP 255.255.255.255 in PHP 5 <= 5.0.2. It was fixed in PHP 5.0.3 where it returns -1 (same as PHP 4).