note 112377 added to function.pack

Useful function to swap bytes in long using pack/unpack: <?php function bswap($long) { // Convert long to 4-byte string in native byte order, // unpack string to array with 4 elements (indices are started from 1 sic!): $x = unpack("C4", pack("L", $long)); // Swap array elements and pack into 4-byte string, // convert string to long in native byte order: // PHP don't allow to use brackets ([]) after function call. So we need to use temp variable: $x2 = unpack("L", pack("C4", $x[4], $x[3], $x[2], $x[1])); return $x2[1]; } ?> Unfortunatelly function can't be minified without using a lot of arithmetic and bit masks. <?php // SAMPLE USAGE: $ip1 = '65.66.67.168'; $ip2 = long2ip(bswap(ip2long($ip1))); echo "ip1 = $ip1\n"; echo "ip2 = $ip2\n"; // output: // ip1 = 65.66.67.168 // ip2 = 168.67.66.65 ?> ---- Server IP: 69.147.83.199 Probable Submitter: 78.129.223.36 ---- Manual Page -- http://php.net/manual/en/function.pack.php Edit -- https://master.php.net/note/edit/112377 Del: integrated -- https://master.php.net/note/delete/112377/integrated Del: useless -- https://master.php.net/note/delete/112377/useless Del: bad code -- https://master.php.net/note/delete/112377/bad+code Del: spam -- https://master.php.net/note/delete/112377/spam Del: non-english -- https://master.php.net/note/delete/112377/non-english Del: in docs -- https://master.php.net/note/delete/112377/in+docs Del: other reasons-- https://master.php.net/note/delete/112377 Reject -- https://master.php.net/note/reject/112377 Search -- https://master.php.net/manage/user-notes.php