4_03 notes

notes/4_03/diamond_problem.cpp

+#include <iostream>
+
+using namespace std;
+
+class A {
+public:
+	A() { cout << "Constructing an A" << endl; }
+	A(const A &a) { cout << "Copying an A" << endl; }
+	virtual ~A() { cout << "Destroying an A" << endl; }
+	virtual void print() { cout << "A" << endl; }
+};
+
+class B : public A {
+public:
+	B() { cout << "Constructing an B" << endl; }
+	B(const B &b) { cout << "Copying an B" << endl; }
+	virtual ~B() { cout << "Destroying an B" << endl; }
+	virtual void print() { cout << "B" << endl; }
+};
+
+class C : public A {
+public:
+	C() { cout << "Constructing an C" << endl; }
+	C(const C &c) { cout << "Copying an C" << endl; }
+	virtual ~C() { cout << "Destroying an C" << endl; }
+	virtual void print() { cout << "C" << endl; }
+};
+
+class D : public B, public C {
+public:
+	D() { cout << "Constructing an D" << endl; }
+	D(const D &d) { cout << "Copying an D" << endl; }
+	virtual ~D() { cout << "Destroying an D" << endl; }
+	virtual void print() { cout << "D" << endl; }
+};
+
+int main(int argc, char *argv[]) {
+	return 0;
+}

notes/4_03/inheritance.cpp

+#include <iostream>
+#include <cstdlib>
+
+using namespace std;
+
+/*
+Polymorphism in c++
+
+Only works with references and pointers!
+Cannot get polymorphic behavior with instances
+I.E. Impossible to assign an instance of subclass to an instance of type superclass
+*/
+
+class shape {
+public:
+	int color;
+	virtual double area() = 0;
+	virtual double perimeter() = 0;
+	virtual ~shape() {};
+
+	friend ostream &operator<<(ostream &o, const shape &s);
+	virtual ostream &print(ostream &o) const = 0;
+};
+
+ostream &operator<<(ostream &o, const shape &s) {
+	return s.print(o);
+}
+
+class rectangle : public shape {
+protected:
+	double width, height;
+public:
+	double area() {
+		return width * height;
+	}
+	double perimeter() {
+		return 2 *(width + height);
+	}
+	rectangle() {
+		width = 1;
+		height = 2;
+	}
+	rectangle(double width, double height) {
+		this->width = width;
+		this->height = height;
+	}
+	ostream &print(ostream &o) const {
+		return o << "Rectangle: Width " << width << ", Height " << height << endl;
+	}
+};
+
+/*
+class square : public shape {
+private:
+	double side;
+public:
+	double area() {
+		return side * side;
+	}
+	double perimeter() {
+		return 4 * side;
+	}
+	square() {
+		side = 1;
+	}
+	square(double side) {
+		this->side = side;
+	}
+	ostream &print(ostream &o) const {
+		return o << "Square: Side " << side << endl;
+	}
+};
+*/
+
+class square : public rectangle {
+private:
+public:
+	square() : rectangle(1, 1) { }
+	square(double side) : rectangle(side, side) { }
+	ostream &print(ostream &o) const {
+		return o << "Square: Side " << width << endl;
+	}
+};
+
+int main(int argc, char *argv[]) {
+	square s(4);
+	rectangle r(3, 5);
+	shape *sp = &s;
+	shape &sr = r;
+
+	shape *a[10];
+
+	cout << s << r << endl;
+
+	cout << sp->area() << " " << sp->perimeter() << " "
+		<< sr.area() << " " << sr.perimeter() << endl;
+
+	for (int i = 0; i < 10; i++) {
+		if (rand() % 2) {
+			a[i] = new square(1 + rand() % 10);
+		} else {
+			a[i] = new rectangle(1 + rand() % 10, 1 + rand() % 10);
+		}
+	}
+
+	for (int i = 0; i < 10; i++) {
+		cout << *a[i];
+	}
+
+	return 0;
+}