PHP to generate a short URL principle and code

Principle:

1. The original URL do crc32 check, get the check code.

2. Use sprintf ('%u ') officers transferred Guevara code to convert to unsigned digits.

3.62 Operations for unsigned digits (uppercase and lowercase + digits equal to 62 digits), the remainder is mapped to 62 characters, and the mapped characters are saved. (for example, the remainder is 10, then the mapped character is a,0-9 corresponds to the 0-9,10-35 corresponding a-z,36-61 a-Z)

4. Cycle operation until the value is 0.

5. All mapped characters are spliced, which is the code after the short URL.

The code is as follows:

/** generates a short URL 
* @param  string $url the original URL 
* @return string
/function DWZ ($url) {  
      
    $code = floatval ( sprintf ('%u ', CRC32 ($url));  
      
    $surl = ';  
      
    while ($code) {  
        $mod = Fmod ($code);  
        if ($mod >9 && $mod <=35) {  
            $mod = chr ($mod +);  
        } ElseIf ($mod >35) {  
            $mod = chr ($mod +);  
        }  
        $surl. = $mod;  
        $code = Floor ($code/62);  
      
    return $surl;  
      
}

Demo

<?php  
Echo dwz (' Http://blog.csdn.net/fdipzone ');//rs5u24  
?>

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