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 8.5.5 PHP 8.5.5 是 PHP 8.5 分支的维护更新版本。该版本延续了“小步快跑”的迭代逻辑，通过深度错误修复、底层性能微调以及安全加固，旨在为开发者提供一个更健壮、更高效的运行环境。该版本严格遵守语义化版本规范，不包含破坏性变更。
下载复制代码代码如下: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.
源码：
复制代码代码如下: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* @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 ($passKey !== null) {// Although this function's purpose is to just make the// ID short - and not so much secure,// with this patch by Simon Franz (http://blog.snaky.org/)// you can optionally supply a password to make it harder// to calculate the corresponding numeric IDfor ($n = 0; $n$i[] = substr( $index,$n ,1);}$passhash = hash('sha256',$passKey);$passhash = (strlen($passhash) ? hash('sha512',$passKey): $passhash;for ($n=0; $n $p[] = substr($passhash, $n ,1);}array_multisort($p, SORT_DESC, $i);$index = implode($i);}$base = strlen($index);if ($to_num) {// Digital number $in = strrev($in);$out = 0;$len = strlen($in) - 1;for ($t = 0; $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;}