PHP生成指定随机字符串的简单实现方法

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/**

* @param string $type

* @param $length

* @return string

*/

function randomString($type="number,upper,lower",$length){

$valid_type = array('number','upper','lower');

$case = explode(",",$type);

$count = count($case);

//根据交集判断参数是否合法

if($count !== count(array_intersect($case,$valid_type))){

return false;

}

$lower = "abcdefghijklmnopqrstuvwxyz";

$upper = strtoupper($lower);

$number = "0123456789";

$str_list = "";

for($i=0;$i<$count;++$i){

$str_list .= $$case[$i];

}

return substr(str_shuffle($str_list),0,$length);

}

echo randomString("number,upper,lower",12);