PHP把数字ID转字母ID
PHP把数字ID转字母ID
ID是网站中经常出现的，它一般是数字，但是我们发现现在的网站很多ID都是字母了,比如YouTube的视频播放页它的URL类似/watch?v=yzNjIBEdyww。 下面是一个生成字母ID的方法。
使用示例：
<?php/** * Translates a number to a short alhanumeric version * * Translated any number up to 9007199254740992 * to a shorter version in letters e.g.: * 9007199254740989 --> PpQXn7COf * * specifiying the second argument true, it will * translate back e.g.: * PpQXn7COf --> 9007199254740989 * * this function is based on any2dec && dec2any by * fragmer[at]mail[dot]ru * see: http://nl3.php.net/manual/en/function.base-convert.php#52450 * * If you want the alphaID to be at least 3 letter long, use the * $pad_up = 3 argument * * In most cases this is better than totally random ID generators * because this can easily avoid duplicate ID's. * For example if you correlate the alpha ID to an auto incrementing ID * in your database, you're done. * * The reverse is done because it makes it slightly more cryptic, * but it also makes it easier to spread lots of IDs in different * directories on your filesystem. Example: * $part1 = substr($alpha_id,0,1); * $part2 = substr($alpha_id,1,1); * $part3 = substr($alpha_id,2,strlen($alpha_id)); * $destindir = "/".$part1."/".$part2."/".$part3; * // by reversing, directories are more evenly spread out. The * // first 26 directories already occupy 26 main levels * * more info on limitation: * - http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/165372 * * if you really need this for bigger numbers you probably have to look * at things like: http://theserverpages.com/php/manual/en/ref.bc.php * or: http://theserverpages.com/php/manual/en/ref.gmp.php * but I haven't really dugg into this. If you have more info on those * matters feel free to leave a comment. * * @author Kevin van Zonneveld <kevin@vanzonneveld.net> * @author Simon Franz * @author Deadfish * @copyright 2008 Kevin van Zonneveld (http://kevin.vanzonneveld.net) * @license http://www.opensource.org/licenses/bsd-license.php New BSD Licence * @version SVN: Release: $Id: alphaID.inc.php 344 2009-06-10 17:43:59Z kevin $ * @link http://kevin.vanzonneveld.net/ * * @param mixed $in String or long input to translate * @param boolean $to_num Reverses translation when true * @param mixed $pad_up Number or boolean padds the result up to a specified length * @param string $passKey Supplying a password makes it harder to calculate the original ID * * @return mixed string or long */function alphaID($in, $to_num = false, $pad_up = false, $passKey = null){ $index = "abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"; if ($passKey !== null) { // Although this function's purpose is to just make the // ID short - and not so much secure, // with this patch by Simon Franz (http://blog.snaky.org/) // you can optionally supply a password to make it harder // to calculate the corresponding numeric ID for ($n = 0; $n<strlen($index); $n++) { $i[] = substr( $index,$n ,1); } $passhash = hash('sha256',$passKey); $passhash = (strlen($passhash) < strlen($index)) ? hash('sha512',$passKey) : $passhash; for ($n=0; $n < strlen($index); $n++) { $p[] = substr($passhash, $n ,1); } array_multisort($p, SORT_DESC, $i); $index = implode($i); } $base = strlen($index); if ($to_num) { // Digital number <<-- alphabet letter code $in = strrev($in); $out = 0; $len = strlen($in) - 1; for ($t = 0; $t <= $len; $t++) { $bcpow = bcpow($base, $len - $t); $out = $out + strpos($index, substr($in, $t, 1)) * $bcpow; } if (is_numeric($pad_up)) { $pad_up--; if ($pad_up > 0) { $out -= pow($base, $pad_up); } } $out = sprintf('%F', $out); $out = substr($out, 0, strpos($out, '.')); } else { // Digital number -->> alphabet letter code if (is_numeric($pad_up)) { $pad_up--; if ($pad_up > 0) { $in += pow($base, $pad_up); } } $out = ""; for ($t = floor(log($in, $base)); $t >= 0; $t--) { $bcp = bcpow($base, $t); $a = floor($in / $bcp) % $base; $out = $out . substr($index, $a, 1); $in = $in - ($a * $bcp); } $out = strrev($out); // reverse } return $out;}