Why C++ doesn't allow this?

[transcendental]

#include <iostream.h>
#include <stdlib.h>

class fourpoint
{
   public:
   int w,x,y,z;


   fourpoint();
   fourpoint(int w,int x,int y,int z);
   ~fourpoint();




} ;
fourpoint::fourpoint()
{

}
fourpoint::fourpoint(int w=0,int x=0,int y=0,int z=0)
{
    this->w=w;
    this->x=x;
    this->y=y;
    this->z=z;


}

fourpoint::~fourpoint()
{


}



int main()
{

      fourpoint *sh= new fourpoint(40,40);
      cout<<endl<< sh->w <<" "<< sh->x;
      cout<< " "<< sh->y <<" "<< sh->z<<endl<<endl;
      system("PAUSE");
      return 0;
}

I can't do this

fourpoint *sh= new fourpoint( , ,40,40);//error

Looks like not very flexible to me as it allows no parameters for the back but it needs you to put parameters in front even though the value of front parameters is default.

p.s. the above program doesn't do anything useful, it was written by me to test whether no front parameters works or not.

[[praetorian]]

Maybe it takes the " , , "as non defined values at all and return errors therefore......?

[filburt1]

I think optional arguments have to be the last arguments for this very reason. VB actually did somethinge better than C++!

[Sastraxi]

Hehe, don't you know it. I think C++ is expecting something like praetorian said, so that you're getting an error. VB did do something right after all!

[kedaman]

You can do some tricks with templates and overloading, but the syntax will be a bit different.

[[praetorian]]

Kedaman,
do you have any examples of that?

[goudabuddha]

Originally posted by filburt1
I think optional arguments have to be the last arguments for this very reason. VB actually did somethinge better than C++!

Finally!!

[parksie]

Yes, but C++ is considerably, considerably, faster than VB

[ravcam]

I am not sure...

but i think all you have to do to overload the constructor function is to create another prototype...

[kedaman]

my Bork expression templates does this for example, but it's not quite simple, besides it requires typing everything.

To pass two same datatypes in a specific order you need overloaded functions, and to distinguish the order your parameterize it. Another way would be to force typing for parameters, which is what Bork is doing.

Btw, it's trickier if you use MSVC, since it has to deduce what parameters are used for the overloaded functions, but you can force to use explicit <> parameterisation if you make a default value for a parameter passed, it's not ANSI compliant but that's MSVC for you