Trigger other tasks after task is complete or had exception

The following example shows how to start a task in a separate thread. Then, using the 'ContinueWith()' function, fire another task depending on if the first task had an unhandled exception or if the task completed without any unhandled exceptions.

private void button1_Click(object sender, EventArgs e)
{
  System.Diagnostics.Debug.WriteLine("button clicked");

  System.Threading.Tasks.Task<int> ret1 = 
    System.Threading.Tasks.Task.Run(() => this.Task1(this.txtInput.Text));

  // run this task if we had any exceptions.
  var c1 = ret1.ContinueWith<decimal>((antecedant) => 
    this.Task2("error", antecedant), TaskContinuationOptions.OnlyOnFaulted);
  // run this task if we did NOT have any exceptions.
  var c2 = ret1.ContinueWith<decimal>((antecedant) => 
    this.Task3("success", antecedant), TaskContinuationOptions.NotOnFaulted);

  System.Diagnostics.Debug.WriteLine("Exiting Button1_click()");
}

private int Task1(string s)
{
  System.Diagnostics.Debug.WriteLine("Starting Task1");

  // simulate some work
  System.Threading.Thread.Sleep(5000);

  // do something with the string that was passed in.
  int y = 5;

  int x = 0;
  // attempt to convert the string that was passed in to an integer.
  x = Convert.ToInt32(s);

  // divide by the value that was passed in.
  int z = y / x;

  // simulate some more work
  System.Threading.Thread.Sleep(5000);

  System.Diagnostics.Debug.WriteLine("About to finish Task1");

  return z;
}

private decimal Task2(string s, Task<int> antecedant)
{
  System.Diagnostics.Debug.WriteLine("Inside Task2- had exception.");

  // do something with the string that was passed in.
  decimal d = 5;
  if (string.IsNullOrEmpty(s))
  {
       d = 0;
  }
  else
  {
       d = (decimal)s.Length;
  }

  // write the exception messages to the debug output window.
  System.Diagnostics.Debug.WriteLine(antecedant.Exception.Message);
  foreach (var ex in antecedant.Exception.InnerExceptions)
  {
       System.Diagnostics.Debug.WriteLine(ex.Message);
  }

  return d;      
}

private decimal Task3(string p, Task<int> antecedant)
{
  decimal d = 5;      

  System.Diagnostics.Debug.WriteLine("Inside Task3- no exceptions.");

  return d;
}