stlshape.cpp

C++编程思想第二版第一册答案

//: C20:Stlshape.cpp
// From Thinking in C++, 2nd Edition
// Available at http://www.BruceEckel.com
// (c) Bruce Eckel 1999
// Copyright notice in Copyright.txt
// Simple shapes w/ STL
#include <vector>
#include <iostream>
using namespace std;

class Shape {
public:
  virtual void draw() = 0;
  virtual ~Shape() {};
};

class Circle : public Shape {
public:
  void draw() { cout << "Circle::draw\n"; }
  ~Circle() { cout << "~Circle\n"; }
};

class Triangle : public Shape {
public:
  void draw() { cout << "Triangle::draw\n"; }
  ~Triangle() { cout << "~Triangle\n"; }
};

class Square : public Shape {
public:
  void draw() { cout << "Square::draw\n"; }
  ~Square() { cout << "~Square\n"; }
};

typedef std::vector<Shape*> Container;
typedef Container::iterator Iter;

int main() {
  Container shapes;
  shapes.push_back(new Circle);
  shapes.push_back(new Square);
  shapes.push_back(new Triangle);
  for(Iter i = shapes.begin();
      i != shapes.end(); i++)
    (*i)->draw();
  // ... Sometime later:
  for(Iter j = shapes.begin();
      j != shapes.end(); j++)
    delete *j;
} ///:~