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alphaID（12354）；//会将数字转换为字母。alphaID（"PpQXn7COf",true）；//会将字母ID转换为对应的数字。alphaID（12354,false,6）；//指定生成字母ID的长度为6.

<？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.** @authorKevin van Zonneveld <kevin@vanzonneveld.net>* @authorSimon Franz* @authorDeadfish* @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 $* @linkhttp://kevin.vanzonneveld.net/** @param mixed $inString or long input to translate* @param boolean $to_numReverses translation when true* @param mixed $pad_upNumber or boolean padds the result up to a specified length* @param string$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 （$passKey ！== null） {// Although this function"s purpose is to just make the// ID short - and not so much secure,// with this patch by Simon Franz （http://blog.snaky.org/）// you can optionally supply a password to make it harder// to calculate the corresponding numeric IDfor （$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, $n ,1）;}//unity3d脚本：http://www.unitymanual.com// http://www.bianceng.cnarray_multisort（$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 codeif （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;}