php随机数代码：php生成随机数与随机字符串的例子

2. /**
3. * @param string $type
4. * @param $length
5. * @return string
6. */
7. function randomString($type="number,upper,lower",$length){
8. $valid_type = array('number','upper','lower');
9. $case = explode(",",$type);
10. $count = count($case);
11. //根据交集判断参数是否合法
12. if($count !== count(array_intersect($case,$valid_type))){
13. return false;
14. }
15. $lower = "abcdefghijklmnopqrstuvwxyz";
16. $upper = strtoupper($lower);
17. $number = "0123456789";
18. $str_list = "";
19. for($i=0;$i $str_list .= $$case[$i];
20. }
21. return substr(str_shuffle($str_list),0,$length);
22. }
23. echo randomString("number,upper,lower",12);

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