Weibo short link algorithm php version, Weibo algorithm php_PHP tutorial

Weibo short link algorithm php version and Weibo algorithm php. The php version of the Weibo short link algorithm and the php idea of the Weibo algorithm: 1) generate a 32-bit signature string for the long URL md5, which is divided into four sections, each of which is 8 bytes; 2) take 8 bytes for this four-step loop processing and regard him as the php version of the Weibo short link algorithm and the Weibo algorithm php

Ideas:
1) generate a 32-bit signature string for the long URL md5, which is divided into four sections, each of which contains 8 bytes;
2) for these four cycles, take 8 bytes and treat them as hexadecimal strings and 0x3fffffff (30 bits 1) and operations, that is, ignore processing with over 30 bits;
3) The 30 digits are divided into six segments. each of the five digits is used as an index of the alphabet to obtain a specific character, and six strings are obtained in sequence;
4) the total md5 string can be 4 6-bit strings; any one of them can be used as the short url address of this long url;

The following is the PHP code:

function shorturl($url='', $prefix='', $suffix='') {    $base32 = 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');     $hex = md5($prefix.$url.$suffix);    $hexLen = strlen($hex);    $subHexLen = $hexLen / 8;    $output = array();     for ($i = 0; $i < $subHexLen; $i++) {        $subHex = substr ($hex, $i * 8, 8);        $int = 0x3FFFFFFF & (1 * ('0x'.$subHex));        $out = '';        for ($j = 0; $j < 6; $j++) {            $val = 0x0000001F & $int;            $out .= $base32[$val];            $int = $int >> 5;        }        $output[] = $out;    }    return $output;} $urls = shorturl('http://www.dareng.com');var_dump($urls);

Result:

array(4) {  [0]=>  string(6) "alms1l"  [1]=>  string(6) "2ipmby"  [2]=>  string(6) "avo1hu"  [3]=>  string(6) "fdlban"}

Tips: 1) generate a 32-bit signature string for the long URL md5, which is divided into four sections, each of which is 8 bytes; 2) process these four sections cyclically and take 8 bytes, think of him...