ip2long() returns a string. Converting this value to float for obtain large precision, you will have the expected result.

$ip = "213.10.212.144";
$ipaddr = sprintf("%u", ip2long($ip));
$address = sprintf("IP ADDR = %u", (float) $ipaddr);

var_dump(PHP_INT_MAX, ip2long($ip), $ipaddr, $address);

--
int(2147483647)
int(-720710512)
string(10) "3574256784"
string(20) "IP ADDR = 3574256784"

Ops, ignore the part "ip2long() returns a string."

@felipe... you're wrong here - this works just fine without having to cast to float:

derick@kossu:~$ php-5.2.5RC2 

<?php
$ip = "213.10.212.144";
$ipaddr = sprintf("%u",ip2long($ip));
$address = sprintf("IP ADDR = %u", $ipaddr);
echo $address;
?>

IP ADDR = 3574256784d

I'm using PHP 5.3.0-dev (cli) (built: Dec 25 2007 10:07:55), and the convertion was necessary.

Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

Nothing is wrong here:

$ip = \"213.10.212.144\";
var_dump(ip2long( $ip ) );

returns: int(-720710512)

$ip = \"213.10.212.144\";
$ipaddr = sprintf(\"%u\",ip2long($ip));
var_dump( $ipaddr );

returns: string(10) \"3574256784\"

Using a string that does not fit in the integer range as a number (with %d or %u) does not work, as the string itself is first converted to an integer - which won\'t work as it doesn\'t fit. You shouldn\'t simply use %u for the returned variable from sprintf() - as it\'s not a n integer, but a string (so use %s).