Thread: type class question 1

Ok If I define a new class called bike. I have two bike objects: x,y and I want the expression x+y to be a new object of the class. What is the prototype of the function that i would write to use the expression x+y?

Code:

bike operator+(const bike& lhs, const bike& rhs);

This function might need to be a friend of your bike class if it requires access to private or protected data.

Originally Posted by jlou

Code:

bike operator+(const bike& lhs, const bike& rhs);

This function might need to be a friend of your bike class if it requires access to private or protected data.

thanks jlou

what do the lhs and rhs mean in the code you provided

if i do delcare this as type friend then would that precede "bike" in your code?

thanks again

also is this just a case of overloading operator?

Here is Sutter's canonical form of operator+:

Code:

T& T::operator+=( const T& other )
{
  // ... All addition work goes here.
  return *this;
}

const T operator+( const T& a, const T& b )
{
  T temp( a );
  temp += b;
  return temp;
}

Among other things, it keeps the addition code confined to the operator+= so that if you have to update it you only have to change one place. This assumes that you have a working copy constructor, or the default copy constructor is sufficient.

Originally Posted by jlou

Here is Sutter's canonical form of operator+:

Code:

T& T::operator+=( const T& other )
{
  // ... All addition work goes here.
  return *this;
}

const T operator+( const T& a, const T& b )
{
  T temp( a );
  temp += b;
  return temp;
}

Among other things, it keeps the addition code confined to the operator+= so that if you have to update it you only have to change one place. This assumes that you have a working copy constructor, or the default copy constructor is sufficient.

well I am very new at c++ and that seems a little out of my element for the time being, is there a simple way to explain that? I am just trying practice excercises here, thanks, sorry if I come off as silly

ok, so is there a more basic prototype to use then canoical form you provided? I am just taking notes on some standard prototypes in certain situations to prepare for self test

I'm not sure what you mean by more basic. I guess a simpler approach would be my first suggestion, especially if you only want to implement operator+.

Code:

class bike
{
public:
  bike() : data(0) { }
  friend bike operator+(const bike& lhs, const bike& rhs);
private:
  int data;
};

bike operator+(const bike& lhs, const bike& rhs)
{
  bike temp;
  temp.data = lhs.data + rhs.data;
  return temp;
}

One word: Tandem

Tandem bikes are the ones with two seats...