// pointer to classes example
#include <iostream>
using namespace std;

class Rectangle {
  int width, height;
public:
  Rectangle(int x, int y) : width(x), height(y) {}
  int area(void) { return width * height; }
};


int main() {
  Rectangle obj (3, 4);
  Rectangle * foo, * bar, * baz;
  foo = &obj;
  bar = new Rectangle (5, 6);
  baz = new Rectangle[2] { {2,5}, {3,6} };
  cout << "obj's area: " << obj.area() << '\n';
  cout << "*foo's area: " << foo->area() << '\n';
  cout << "*bar's area: " << bar->area() << '\n';
  cout << "baz[0]'s area:" << baz[0].area() << '\n';
  cout << "baz[1]'s area:" << baz[1].area() << '\n';       
  delete bar;
  delete[] baz;
  return 0;
}	

　　运行结果：

obj's area: 12
*foo's area: 12
*bar's area: 30
baz[0]'s area:10
baz[1]'s area:18

　　指向class的指针。

This example makes use of several operators to operate on objects and pointers (operators *, &, ., ->, []). They can be interpreted as:

 

expression	can be read as
*x	pointed to by x
&x	address of x
x.y	member y of object x
x->y	member y of object pointed to by x
(*x).y	member y of object pointed to by x (equivalent to the previous one)
x[0]	first object pointed to by x
x[1]	second object pointed to by x
x[n]	(n+1)th object pointed to by x

Most of these expressions have been introduced in earlier chapters. Most notably, the chapter about arrays introduced the offset operator ([]) and the chapter about plain data structures introduced the arrow operator (->).