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例1，php生成短网址。
-
- $chars=array("a","b","c","d","e","f","g","h",
- "i","j","k","l","m","n","o","p",
- "q","r","s","t","u","v","w","x",
- "y","z","0","1","2","3","4","5",
- "6","7","8","9","A","B","C","D",
- "E","F","G","H","I","J","K","L",
- "M","N","O","P","Q","R","S","T",
- "U","V","W","X","Y","Z");
- $salt="www.joneto.com";
- $hash=md5("http://bbs.it-home.org".$salt);
- $rs=array();
- for($i=0;$i<4;$i++){
- $temp=substr($hash, $i*8,8);
- $temp=base_convert($temp, 16, 10) & base_convert("3fffffff", 16, 10);
- $str="";
- for($j=0;$j<6;$j++){
- $subtemp=$temp & intval(base_convert("3d", 16, 10));
- $str.=$chars[$subtemp];
- $temp=$temp>>5;
- }
- unset($temp);
- $rs[]=$str;
- }
- print_r($rs);
- ?>
php 生成短网址原理及代码
将原网址做crc32校验，得到校验码，使用sprintf将校验码转为无符号数字。
php 生成短网址 原理：
1.将原网址做crc32校验，得到校验码。
2.使用sprintf('%u') 将校验码转为无符号数字。
3.对无符号数字进行求余62操作（大小写字母+数字等于62位），得到余数后映射到62个字符中，将映射后的字符保存。（例如余数是10，则映射的字符是A，0-9对应0-9，10-35对应A-Z，35-62对应a-z）
4.循环操作，直到数值为0。
5.将所有映射后的字符拼接，就是短网址后的code。
-
-
/** 生成短网址 - * @param String $url 原网址
- * @return String
- */
- function dwz($url){
$code = sprintf('%u', crc32($url)); $surl = ''; while($code){ - $mod = $code % 62;
- if($mod>9 && $mod<=35){
- $mod = chr($mod + 55);
- }elseif($mod>35){
- $mod = chr($mod + 61);
- }
- $surl .= $mod;
- $code = floor($code/62);
- }
- return $surl;
- }
-
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