time difference

You can use the TotalHours property to get the total hours worked including any fractional hours.

Also, if the times are to be presented in exactly that format (i.e. separated by a dot instead of a colon), then you'll need to specify the format to be used, otherwise you'll get an exception:

      string format = "h.m tt";
      DateTime startTime = DateTime.ParseExact("9.30 AM", format, null);
      DateTime endTime = DateTime.ParseExact("4.30 Pm", format, null); 
      double totalTime = (endTime - startTime).TotalHours;
      Response.Write(String.Format("Total time worked is {0} hours", totalTime));

protected void Button1_Click(object sender, EventArgs e)
    {
        DateTime dt1 = Convert.ToDateTime("9:30 am");
        DateTime dt2 = Convert.ToDateTime("10:00 pm");
        TimeSpan ts = dt2 - dt1;
        Response.Write(ts.ToString());
    }

if the time difference gores more than one day you can get hours by
 ts.hours.tostring(); and minuts by
 ts.minuts.tostring();

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