operator++(?)

[Anonymous]

class counter
{ int amount;
  public:
  counter() { amount=0; }
  counter operator++(?) //why does it have to be " counter operator++(int) "
                       //not " counter operator++(void) "
     { amount++; return *this; }
};

main()
{
counter a;
a++;
}

[Anonymous]

so maybe anyone could tell me how to use ++ operator with friend and without friend function:
1) ++(something) using friend function
2) (something)++ using friend
3) ++(something) not using friend function
4) (something)++ -"-

[Anonymous]

i guess if i want to use ++(something) operator, i have to use friend function, and (something)++ can t be defined using friend function.

my program:

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

class counter
{ int amount;
  public:
  void show() { cout << amount << "\n\n"; }
  counter() { amount=0; }
  counter operator++(int) { amount++; return *this; }
  friend counter operator++(counter& x) { x.amount++; return x; }
};

main()
{
counter object;
object++;
++object;
object.show();
system("pause");
}

am i right??