Re: SqlDataReader do I need to call close?

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sorry, but i need to be sure, lets say i use this snippet:
Connection.Open();
dr=cmd.ExecuteReader();
if(dr.Read())
str=dr[0].ToString();
Connection.Close();
/// end of page rpocessing in ASP.Net
will it be working ok? connection closed, datareader will dispose as going
out of scope? i'm not asking about best practice now but about do i need to
review bulk of code and projects to add dr.Close() everywhere or I can leave
it as is, as far as it seem to work and connections are closed without
calling dr.close()? or may be there is still some resource leak or somthing?
thank you.
.