overhead.cpp

来自「Think in C++文中代码实现」· C++ 代码 · 共 69 行

// File from page 658 in "Thinking in C++" by Bruce Eckel
//////////////////////////////////////////////////
// From the compressed package ECKELT02.ZIP 4/11/95
// (Original ECKELT01.ZIP dated 2/21/95)
// Copyright (c) Bruce Eckel, 1995 
// Source code file from the book "Thinking in C++", 
// Prentice Hall, 1995, ISBN: 0-13-917709-4
// All rights reserved EXCEPT as allowed by the following 
// statements: You may freely use this file for your own 
// work, including modifications and distribution in 
// executable form only. You may copy and distribute this 
// file, as long as it is only distributed in the complete 
// (compressed) package with the other files from this 
// book and you do not remove this copyright and notice. 
// You may not distribute modified versions of the source 
// code in this package. This package may be freely placed 
// on bulletin boards, internet nodes, shareware disks and 
// product vendor disks. You may not use this file in 
// printed media without the express permission of the 
// author. Bruce Eckel makes no 
// representation about the suitability of this software 
// for any purpose. It is provided "as is" without express 
// or implied warranty of any kind. The entire risk as to 
// the quality and performance of the software is with 
// you. Should the software prove defective, you assume 
// the cost of all necessary servicing, repair, or 
// correction. 
// If you think you've found an error, please 
// email all modified files with loudly commented changes 
// to: [e-mail] (please use the same 
// address for non-code errors found in the book).
//////////////////////////////////////////////////

//: OVERHEAD.CPP -- Virtual base class overhead
#include <fstream.h>
ofstream out("overhead.out");

class base {
public:
  virtual void f() const {};
};

class nonvirtual_inheritance 
  : public base {};

class virtual_inheritance 
  : virtual public base {};

class virtual_inheritance2 
  : virtual public base {};

class mi 
  : public virtual_inheritance,
    public virtual_inheritance2 {};

#define WRITE(arg) \
out << #arg << " = " << arg << endl;

main() {
  base b;
  WRITE(sizeof(b));
  nonvirtual_inheritance nonv_inheritance;
  WRITE(sizeof(nonv_inheritance));
  virtual_inheritance v_inheritance;
  WRITE(sizeof(v_inheritance));
  mi MI;
  WRITE(sizeof(MI));
}