2 questions for help!

[Birt]

1. When defining only a copy constructor but no other constructors, the
default constructor will not be available any more in a class?

2.
class CEngine
{
....
public
// CEngine();//Without this, error happens
CEngine(int volume);
....
};


class CFord : public CCar
{
CEngine e;

public:
CFord(const CFord& f);
CFord& operator=(const CFord& f);
....
};

When adding CFord(const CFord& f); into CFord, the error happens:

error C2512: 'CEngine' : no appropriate default constructor available.

To solve the problem, add a default constructor by myself. Is there any
better solution?

How to force to use the CEngine(int volume) constructor?

 

[Buster]

1. When defining only a copy constructor but no other constructors, the
default constructor will not be available any more in a class?

That's not a question.

2.
class CEngine
{
...
public
// CEngine();//Without this, error happens
CEngine(int volume);
...
};


class CFord : public CCar
{
CEngine e;

public:
CFord(const CFord& f);
CFord& operator=(const CFord& f);
...
};

When adding CFord(const CFord& f); into CFord, the error happens:

error C2512: 'CEngine' : no appropriate default constructor available.

To solve the problem, add a default constructor by myself. Is there any
better solution?

Well, there was a default constructor before (the implicitly declared
default constructor), and you were using it, so why not have a default
constructor now? Are you sure you no longer need one?

How to force to use the CEngine(int volume) constructor?

Pass an integer argument when the CEngine object is created. Data
members are initialized before the body of the constructor is entered,
so there is a special syntax for passing arguments to data member
constructors:

int some_integer = 0;

CFord::CFord (const CFord & f)
: e (some_integer)
{
// constructor body
}