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Exception Handling

• It's a good idea to use inheritance to define your own exception types.

  class FutureValueError : public logic_error
  {
  
  public:
     FutureValueError(const char reason[]);
  };
  
  FutureValueError::FutureValueError(const char reason[])
     : logic_error(reason){}
  

• Here, the future_value function can now throw a FutureValueError object.

  if (p < 0 || n < 0)
     throw FutureValueError("illegal parameter");
  

• BecauseFutureValueError is a logic_error, you can still catch it with catch (logic_error& e).
• You can even catch other types of errors. Note that the exception handling mechanism matches the handlers top to button, and executes the first matching handler.

  try
  {
     code
  }
  catch (FutureValueError& e)
  {
     handler1
  } 
  catch (logic_error& e)
  {
     handler2
  }
  

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