🚀 go-pugleaf

Hi,

I think you can declare the ptr as a static member of the class Object.
Then it will act as a global variable in all the instances of the class.

The code will be something like:

#include <iostream.h>

class Object
{ public:
     int id;
     static Object *ptr;//declare the ptr as a static member
	 Object(int);
	 void show(){ cout<<"this is "<<id<<endl;};
 };

 Object::Object(int idnum)
 {
      id = idnum;
      ptr = this;
 }

 Object *Object::ptr=new Object(0);//define and initialize "ptr"

 main()
 {Object(1);
  Object::ptr->show();//show 1
  Object * p=new Object(2);
  Object::ptr->show();//show 2

  return 0;

 }


 Good luck



In article <S3be3.496$nZ5.796@nntpserver.swip.net>,
  "Magnus Hult" <hult.holmstrom@swipnet.se> wrote:
> Hello,
> I've got this class, Object. It looks like this (well, it's more
> complicated, but you'll get the essence):
>
> class Object {
>     public:
>         int id;
>         Object(int idnum) {
>             id = idnum;
>             ptr = this;            // Let the pointer point to the
newly
> created instance
>         }
> };
>
> And ptr is supposed to be a global varible declared like "Object
*ptr". The
> problem is that I can't declare it before the class definition, cause
then
> my old Borland 4.51 doesn't know what an "Object" is. But I can't
declare it
> after the class definition either, cause then I've already used the
pointer
> in the class without telling C++.
> The only way I've been able to get through this problem is to do like
this:
>
> class Object {
>     public:
>         int id;
>         Object(int);
> };
>
> Object *ptr;            // Here C++ knows what an Object is, and I
haven't
> used ptr yet
>
> Object::Object(int idnum) {
>     id = idnum;
>     ptr = this;
> }
>
> which isn't a very smooth solution, since I might be needing more
variables
> and classes like this. I thought it didn't matter where in the code I
> declare variables and so on, but apparently it does. Is my compiler
too old,
> or is there a better way to solve the problem?
>
> thanks,
> Magnus Hult
> hult.holmstrom@swipnet.se
> http://www.ovenproof.com
>
>


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