How to convert integer number to ip address in php

In the field of web development, we often need to convert integer numbers into IP addresses, such as recording the user's registered IP when registering, or when analyzing web access logs, we need to convert the IP address into an integer for query, etc. . In response to this need, PHP provides convenient ip2long() and long2ip() functions.

The ip2long() function converts an IPv4 address into a long integer number (32-bit signed integer), while the long2ip() function converts a long integer number into an IPv4 address.

$ip = '192.168.0.1';
$long = ip2long($ip);
echo $long.PHP_EOL; // Output: -1062731775

$long = -1062731775;
$ip = long2ip($long);
echo $ip.PHP_EOL; // Output: 192.168.0.1
?>

But it should be noted that these two functions only support IPv4 addresses. If you need to handle IPv6 addresses, you need to use other methods to achieve it. In addition, PHP uses network byte order (big-endian) when processing IP addresses and integer number conversions.

Network byte order refers to the byte order specified in the TCP/IP protocol stack, and the bytes are arranged in a big-endian manner. The so-called big endian means that the high-order byte comes first and the low-order byte comes last. For example, an integer 0x12345678 is represented as 0x12, 0x34, 0x56, 0x78 in network byte order.

How to convert ip address into integer?

To convert an ip address into an integer, you can use the following method:

function ip2long_v2($ip) {

$ipArr = explode(".", $ip); // 将IP地址拆分成数组
$num = 0;
foreach ($ipArr as $k => $v) {
    $num = $num << 8; // 左移8位 
    $num += intval($v); // 叠加 
}
return $num;

}
?>

This function splits the IP address into an array, then shifts and superimposes each digit, and finally converts it into an integer.

How to convert an integer into an ip address?

To convert an integer into an IP address, you can use the following method:

function long2ip_v2($long) {

$arr = array(
    ($long & 0xff000000) >> 24,
    ($long & 0x00ff0000) >> 16,
    ($long & 0x0000ff00) >> 8,
    ($long & 0x000000ff)
);
return implode('.', $arr);

}
?>
This function converts the integer into an array after bitwise operation, and then connects the array into an ip address. 
Summary
PHP provides convenient ip2long() and long2ip() functions, which can convert IP addresses and integers to and from each other. However, it should be noted that these two functions only support IPv4 addresses and use network byte order. If you need to handle IPv6 addresses, you need to use other methods to achieve it. 
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