C#

using Core = Microsoft.Office.Core;
using Word = Microsoft.Office.Interop.Word;
using Excel = Microsoft.Office.Interop.Excel;

        private void button1_Click(object sender, EventArgs e)
        {
            object oMissing = System.Reflection.Missing.Value;
            Word.Application app = new Word.ApplicationClass();
            app.Visible = true;
            Word.Document doc = app.Documents.Add(ref oMissing, ref oMissing, ref oMissing, ref oMissing);
            Word.Range rng = doc.Content;
            rng.InsertAfter("Some text.");
            rng.InsertParagraphAfter();
            rng.InsertAfter("new paragraph");
        }

        private void button2_Click(object sender, EventArgs e)
        {
            try
            {
                object oMissing = System.Reflection.Missing.Value;
                Excel.Application app = new Excel.ApplicationClass();
                app.Visible = true;
                Excel.Workbook wb = app.Workbooks.Add(oMissing);//here is the error
            }
            catch (Exception error)
            {
                MessageBox.Show(error.ToString());
            }
        }

private static void DoStuff()
{
  int x = 0, y = 0, z = 0;

  Function1();
  x = Function2();
  if(x > y)
    Function3();
}

private static void ExecProc(int vidID)
{
  try
  {
    SqlCommand cmd  = new SqlCommand("blah", conn);
    cmd.CommandType = CommandType.StoredProcedure;
    cmd.Parameters.Add(new SqlParameter("@vidID", vidID));
    cmd.ExecuteNonQuery();
  }
  catch (Exception e)
  {
    Console.WriteLine("error: " + e.ToString());
  }
}

Object reference not set to an instance of an object

XElement data = (from node in X_Element.Descendants(nodeName)
                 select node).First();
Clipboard.Clear();
Clipboard.SetData("XElement", data);
XElement newXmlNode = (XElement)Clipboard.GetData("XElement");
MessageBox.Show(newXmlNode.Name.ToString());