Question

I saw my friend doing some Web Development, and one of his code caught my attention is the Response.Redirect.

What is the use of Home?=, isn’t it the LogIn.aspx is the name of the page how come it’s still redirecting if it has Home?=. Can someone answer this question of mine please, and explain it very well.

String url = "LogIn.aspx?Home?=" + Username;
Response.Redirect(url);

Answer 1

Update

Working from all your comments, the answer is: The query string parameter name (key) is actually "Home?", not just "Home". Details (including why the code generating that is technically incorrect) below.

how come it’s still redirecting if it has Home?=?

Because there’s no reason it shouldn’t redirect. Granted the URL is invalid (? is a reserved character, it cannot appear unencoded in the query string, so the second ? in the URL is incorrect), but browsers are pretty content to deal with invalid URLs.

Separately, unless Username has already been URL-encoded, the URL could have other errors depending on the content of Username. (All query string parameters must be URL-encoded, in .Net you do that with HttpUtility.UrlEncode.)

Re your comment:

what i mean is i don’t know why he use Home?= and what is the use of it

It has no use, it’s an error. He probably just meant (no, apparently not, see below after your next comment)

String url = "LogIn.aspx?Home=" + Username;

…which would more correctly be:

String url = "LogIn.aspx?Home=" + HttpUtility.UrlEncode(Username);

(Technically, you have to URL-encode both the keys and values [both "Home" and Username], but the URL-encoded form of "Home" is "Home", so we can get away without making the call for the key. Not true if the key needs to have any of the URL reserved characters in it.)

Re your further comment consisting entirely of this code:

string retrieveValue;
protected void Page_Load(object sender, EventArgs e) {
    this.lblUsername.Text = Request.QueryString["Home?";
    retrieveValue = this.lblUsername.Text;
}

Assuming the syntax error in the above is fixed (missing ] on line 3), it would appear that he’s actually using "Home?" as a key (parameter name). That means the redirect should be:

String url = "LogIn.aspx?" + HttpUtility.UrlEncode("Home?") + "=" + HttpUtility.UrlEncode(Username);

…because the key has a reserved character in it (?). Because that will be decoded for you on receipt, that should make the code above work.

Note that most browsers will probably let you get away with the string as he specified it. It’s incorrect, but in a way browsers probably allow.