如何在此数组中插入字符

foreach ($_GET as $key=>$value) {
  echo "$key=".urldecode($value)."<br/>";
}

the result is:

id=http://google.com/?var=234
k=234
ks=333

How can I insert the "&" in this array so it would output like this.

$param = "id=http://google.com/?var=234&k=234&ks=333";

Use http_build_query()

echo http_build_query($_GET);