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# ip2long

(PHP 4 , PHP 5)

ip2long -- Converts a string containing an (IPv4) Internet Protocol dotted address into a proper address.

## Description

int ip2long ( string ip_address)

The function ip2long() generates an IPv4 Internet network address from its Internet standard format (dotted string) representation. If ip_address is invalid then -1 is returned. Note that -1 does not evaluate as `FALSE` in PHP.

In PHP 5 ip2long() returns FALSE when the ip_address is in valid.

示範 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; ?>`

> 備注: Because PHP's integer type is signed, and many IP addresses will result in negative integers, you need to use the "%u" formatter of sprintf() or printf() to get the string representation of the unsigned IP address.

This second example shows how to print a converted address with the printf() function in PHP 4:

示範 2.Displaying an IP address (PHP 4)
`<?php $ip = gethostbyname("www.example.com"); $long = ip2long($ip); if ($long === -1) { echo "Invalid IP, please try again"; } else { echo $ip . "\n"; // 192.0.34.166 echo $long . "\n"; // -1073732954 printf("%u\n", ip2long($ip)); // 3221234342 } ?>`

This third example shows how to print a converted address with the printf() function in PHP 5:

示範 3.Displaying an IP address (PHP 5)
`<?php $ip = gethostbyname("www.example.com"); $long = ip2long($ip); if ($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 } ?>`

ip2long() will also work with non-complete ip adresses. Read http://publibn.boulder.ibm.com/doc_link/en_US/a_doc_lib/libs/commtrf2/inet_addr.htm for more info.

> 備注: ip2long() will return -1 for the IP 255.255.255.255

See also long2ip() and sprintf().

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