PHP获取随机字符串的两种方法

 1 <?php
 2 /**
 3  * 随机返回字符串
 4  * @param number 返回字符串长度
 5  * @param string 从哪些字符串中随机返回，已设置默认字符串，可空
 6  * @return string 返回随机字符串
 7  */
 8 function random_string($length = 8, $chars = null) {
 9     static $s;
10     if( empty($chars) ) $chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
11     while( strlen($s) < $length) {
12         $s .= substr($chars, rand(0, strlen($chars) - 1), 1);
13     }
14     return $s;
15 }
16 
17 function random_string2($length = 8, $chars_range = 'alpha-number') {
18     $str = '';
19     $chars = '';
20     $char_arr = array(
21             "alpha" => "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz",
22             "number" => "0123456789",
23     );
24     if (empty($chars_range)) {
25         $chars_rang = 'alpha-number';
26     }
27     if(strpos($chars_range, '-')) {
28         $char_range_arr = explode('-',$chars_range);
29         foreach($char_range_arr as $range){
30             if(!array_key_exists($range, $char_arr)){
31                 exit("wrong range \"". $range ."\"");
32             }
33             $chars .= $char_arr[$range];
34         }
35     }else{
36         if(!array_key_exists($chars_range, $char_arr)){
37             exit("wrong range \"".$chars_range ."\"");
38         }
39         $chars = $char_arr[$chars_range];
40     }
41     while( strlen($str) < $length) {
42         $str .= substr($chars, rand(0, strlen($chars) - 1), 1);
43     }
44     return $str;
45 }
46 
47 ?>