inet_ntop()

(PHP 5 >= 5.1.0, PHP 7)

Converts a packed internet address to a human readable representation

说明

inet_ntop(string $in_addr): string

This function converts a 32bit IPv4, or 128bit IPv6 address (if PHP was built with IPv6 support enabled) into an address family appropriate string representation.

参数

$in_addr

A 32bit IPv4, or 128bit IPv6 address.

返回值

Returns a string representation of the address 或者在失败时返回FALSE.

范例

Example #1inet_ntop()Example

<?php
$packed = chr(127) . chr(0) . chr(0) . chr(1);
$expanded = inet_ntop($packed);
/* Outputs: 127.0.0.1 */
echo $expanded;
$packed = str_repeat(chr(0), 15) . chr(1);
$expanded = inet_ntop($packed);
/* Outputs: ::1 */
echo $expanded;
?>

更新日志

参见

• long2ip() 将长整型转化为字符串形式带点的互联网标准格式地址（IPV4）
• ip2long() 将 IPV4 的字符串互联网协议转换成长整型数字
• inet_pton()Converts a human readable IP address to its packed in_addr representation

For people who wondering what the meaning of this function name:
pton: a presentation(printable) format address to network address
ntop: a network address to presentation(printable) format address

PHP's inet_ntop function is not compatible with the binary representation used by MySQL's INET6_ATON function, assuming you are using the recommended method of storing both IPv4 and IPv6 addresses in a VARBINARY(16) field. You need to convert it like this:
/**
 * Convert a MySQL binary v4 (4-byte) or v6 (16-byte) IP address to a printable string.
 * @param string $ip A binary string containing an IP address, as returned from MySQL's INET6_ATON function
 * @return string Empty if not valid.
 */
function inet6_ntop($ip) {
  $l = strlen($ip);
  if ($l == 4 or $l == 16) {
    return inet_ntop(pack('A' . $l, $ip));
  }
  return '';
}
You don't need a function going the other way because MySQL's INET6_NTOA is already compatible with PHP's inet_pton function.

For people who need this function but don't have it, I could write a function which should give almost the same result.
<?php
function my_inet_ntop($ip) {
  if (strlen($ip)==4) {
    // ipv4
    list(,$ip)=unpack('N',$ip);
    $ip=long2ip($ip);
  } elseif(strlen($ip)==16) {
    // ipv6
    $ip=bin2hex($ip);
    $ip=substr(chunk_split($ip,4,':'),0,-1);
    $ip=explode(':',$ip);
    $res='';
    foreach($ip as $seg) {
      while($seg{0}=='0') $seg=substr($seg,1);
      if ($seg!='') {
        $res.=($res==''?'':':').$seg;
      } else {
        if (strpos($res,'::')===false) {
          if (substr($res,-1)==':') continue;
          $res.=':';
          continue;
        }
        $res.=($res==''?'':':').'0';
      }
    }
    $ip=$res;
  }
  return $ip;
}
?>
I followed IPv6 reprenstation rules :
- A series of "0"s in a 16bit block can by represented by "0".
- A series of blocks containing only "0"s can be suppressed and represented by "::" (this can be done only once)
(source : http://www.ipv6style.jp/en/faq/latest.shtml#2003022112 )
Example: 
<?php
$packed = str_repeat(chr(0), 15) . chr(1);
$expanded = my_inet_ntop($packed);
/* Outputs: ::1 */
echo $expanded;
?>
I checked in CVS (2005-04-25) and didn't find the inet_ntop function (I really needed to handle IPv6) so I implemented it myself !

Before inet_pton nice work
//2001:0db8:85a3:0000:0000:8a2e:0370:7334
After
//2001:db8:85a3::8a2e:370:7334
no need compare compress data
string inet_ntop ( string $in_addr [, bool $compress = false] )
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