随机字符生成
function randStr($length=4,$type="1"){
$array = array(
'1'=>'0123456789',
'2'=>'ABCDEFGHIJKLMNOPQRSTUVWXYZ',
'3'=>'0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ',
);
$string = $array[$type];
$count = strlen($string)-1;
$rand ='';
for($i =0; $i < $length; $i++){
$rand .= $string[mt_rand(0, $count)];
}
return $rand;
}