static in classes

hi all,
i want to make a class which can count how many objects it has.
i thougt to use static and one initilaize aftert that incrementing it.

Code:

class x
{
public:
	int no;
	int give_no;
	x();
};

x::x()
{
	no=0;
	give_no++;
	no= give_no;
}

but it gives me error. where am i wrong?

Code:

class x
{
public:
    int no;
    static int give_no;
    x();
};

// You need to declare an instance of each static variable used in a particular class
int x::give_no = 0;

x::x()
{
    no = ++give_no;
}

aff scope operator, thanks. i have a terrible headache.