Copy constructors

[mozly]

So i'm having problems deep copying one vector to another. I have these classes:

struct cloneable
{
        virtual ~cloneable(){}
        virtual cloneable* clone() const = 0;
};

class Digit: public cloneable
{
        protected:
                //x and y positons
                int Xpos;
                int Ypos;
  
                //value in string format
                std::stringstream svalue;
        
  public:
        Digit();
        Digit(const Digit &copy)
{copy.svalue.rdbuf();}

        ~Digit();

//copy fucntion
        virtual Digit* clone() const
    { return new Digit( *this ); }

};


class Realnum: public Digit
{
protected:
        float value;
public:
        Realnum( int  x, int y);
        Realnum(const Realnum &copy): Digit(copy)
        {}
        ~Realnum();

//copy fucntion
Realnum* clone() const
    {return new Realnum( *this);}
};

I have two vectors of type <Digit*>
my copying method now looks like this

for(int i=0; i< equation_buffer.size(); i++)
        {
            undo_vector[i] = equation_buffer[i]->clone();
           
        }

Now my program compiles without error but I have a problem at runtime. The problem now is that the clone() returns something that does not initialize the values in undo_vector[i]
It returns this:
Realnum::clone returned 0x007d7660 {value=-4.3160208e+008 order=-842150451 } Realnum *

where is should return something more like
Realnum::clone returned 0x007d7660 {value=-2 order=0 } Realnum *

[mozly]

plz help :)

[ne555]

Digit::Digit(const Digit &copy){
  copy.svalue.rdbuf(); //statement has no effect
}

Maybe you want this->svalue.str( copy.svalue.str() );