Creating an easy to maintain copy constructor

Question

Consider the following class:

class A {

char *p;
int a, b, c, d;

public:
   A(const &A);
};

Note that I have to define a copy constructor

Answer 1

So the default copy constructor is called first and then the deep copy is performed. Unfortunately this doesn't seem to work.

Is there any better way to do this? One restriction - I can't use shared/smart pointers.

If I understand correctly, your question, you could consider using an initialization function:

class A
{
    int i, j;
    char* p;

    void Copy(int ii, int jj, char* pp); // assign the values to memebers of A
public:
    A(int i, int j, char* p);
    A(const A& a);
};

A::A(int i, int j, char* p)
{
    Copy(i, j, p);
}

A::A(const A& a)
{
    Copy(a.i, a.j, a.p);
}

That said, you really should consider using RAII ( there's a reason people keep recommending it :) ) for your extra resources.

If I can't use RAII, I still prefer creating the copy constructor and using initializer lists, for every member (actually, I prefer doing so even when using RAII):

A::A(int ii, int lj, char* pp)
    : i(ii)
    , j(jj)
    , p( function_that_creates_deep_copy(pp) )
{
}

A::A(const A& a)
    : i(a.i)
    , j(a.j)
    , p( function_that_creates_deep_copy(a.p) )
{
}

This has the advantage of "explicitness" and is easy to debug (you can step in and see what it does for each initialization).