static data members and member functions

class xx {

public:

// stuff deleted...

private:

static int static_member;

int normalmember1;

int normalmember2;

};

Instance of class xx

Instance of class xx

Instance of class xx

static_member

Each instance of the class xx has its own copy of the normalmember1 and normalmember2 variable, but there is only one copy of the static_member variable shared by all instances.

Two important applications of static data members:

• because all instances of a class “see” the same data member, you can use it to globally modify the behavior of all instances of the class;

• a static variable can be set even if no instance of a class exists yet.

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