static void CopyObject(SampleClass original)
{
  if (original == null)
  {
    throw new System.ArgumentException("Parameter cannot be null", "original");
  }

}

class ProgramLog
{
  System.IO.FileStream logFile = null;
  void OpenLog(System.IO.FileInfo fileName, System.IO.FileMode mode) {}

  void WriteLog()
  {
    if (!this.logFile.CanWrite)
    {
      throw new System.InvalidOperationException("Logfile cannot be read-only");
    }
    // Else write data to the log and return.
  }
}

static int GetValueFromArray(int[] array, int index)
{
  try
  {
    return array[index];
  }
  catch (System.IndexOutOfRangeException ex)
  {
    System.ArgumentException argEx = new System.ArgumentException("Index is out of range", "index", ex);
    throw argEx;
  }
}

public class InvalidDepartmentException : System.Exception
{
  public InvalidDepartmentException() : base() { }
  public InvalidDepartmentException(string message) : base(message) { }
  public InvalidDepartmentException(string message, System.Exception inner) : base(message, inner) { }

  // A constructor is needed for serialization when an
  // exception propagates from a remoting server to the client. 
  protected InvalidDepartmentException(System.Runtime.Serialization.SerializationInfo info,
    System.Runtime.Serialization.StreamingContext context) { }
}

 try
{
  // Code to try goes here.
}
catch (SomeSpecificException ex)
{
  // Code to handle the exception goes here.
  // Only catch exceptions that you know how to handle.
  // Never catch base class System.Exception without
  // rethrowing it at the end of the catch block.
}

 try
{
  // Code to try goes here.
}
finally
{
  // Code to execute after the try block goes here.
}

 try
{
  // Code to try goes here.
}
catch (SomeSpecificException ex)
{
  // Code to handle the exception goes here.
}
finally
{
  // Code to execute after the try (and possibly catch) blocks 
  // goes here.
}

int GetInt(int[] array, int index)
{
  try
  {
    return array[index];
  }
  catch(System.IndexOutOfRangeException e)
  {
    throw new System.ArgumentOutOfRangeException(
      "Parameter index is out of range.");
  }
}

try
{
  // Try to access a resource.
}
catch (System.UnauthorizedAccessException e)
{
  // Call a custom error logging procedure.
  LogError(e);
  // Re-throw the error.
  throw;   
}

System.IO.FileStream file = null;
System.IO.FileInfo fileinfo = new System.IO.FileInfo("C:\\file.txt");
try
{
  file = fileinfo.OpenWrite();
  file.WriteByte(0xF);
}
finally
{
  // Check for null because OpenWrite might have failed.
  if (file != null)
  {
    file.Close();
  }
}