ex3-2-1.cpp

来自「一些学习c++的例题」· C++ 代码 · 共 44 行

//From Thinking in C++ Vol 2, Bruce Eckel
//: C11:HowMany.cpp
// A class that counts its objects
#include <iostream>

using namespace std;

class HowMany 
{
private:
  static int objectCount;
public:
  HowMany() { objectCount++; }

  static void print(const char * msg = NULL) 
  {
    if(msg) cout << msg << ": ";
    cout << "objectCount = " << objectCount << endl;
  }

  ~HowMany() 
  {
    objectCount--;
    print("~HowMany()");
  }
};

int HowMany::objectCount = 0;

// Pass and return BY VALUE:
HowMany f(HowMany x) 
{
  x.print("x argument inside f()");
  return x;
}

void main() 
{
  HowMany h;
  HowMany::print("after construction of h");
  HowMany h2 = f(h);
  HowMany::print("after call to f()");
} ///:~