Access Control Example

class employee {

private: // For our eyes only!

char *name_p;

int base_pay_p;

int year_started_p;

int leave_time_p;

public:

employee(); // Constructors MUST be public!

~employee(); // (and destructors too)

void set_name(char *name);

char *name() { return name_p; }

};

employee::employee() { // Constructor!

name_p = NULL;

}

// New set_name() does proper memory mgmt!

employee::set_name(char *name) {

if (name_p != NULL)

free(name_p);

name_p = strdup(name);

}

employee::~employee() { // Destructor!

if (name_p != NULL)

free(name_p);

}

main()

{

employee e, e2; // Constructors called

e.set_name(“John Doe”);

e.set_name(“Jim Smith”); // free() done!

printf(“Name is %s!\n”, e.name());

// This FAILS at compile-time!

e2.name_p = 0xdeadbeef;

} // Destructors called here!

(Note, I’m glossing over the fact that the caller can still change the contents of the string to which name_p points, if not the pointer itself)

Previous slide

Next slide

Back to first slide

View graphic version