请指教指教
<?php
function buildRandomString($type=1,$length=4){
if（$type==1){
$chars=join("",range(0,9));
}elseif($type==2){
$chars=join("",array_merge(range("a","z"),range("A","Z")));
}elseif($type==3){
$chars=join("",array_merge(range("a","z"),range("A","Z"),range(0,9)));
}
if（$length>strlen($chars)){
exit("字符串长度不够");
}
$chars=str_shuffle($chars);
return substr($chars,0,$length);
}
提示第三、五、七、十行有错误，请问错在哪？
