autocc.cpp

Think in C++文中代码实现

// File from page 386 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).
//////////////////////////////////////////////////

//: AUTOCC.CPP -- Automatic copy-constructor
#include <iostream.h>
#include <string.h>

class withCC { // With copy-constructor
public:
  // Explicit default constructor required:
  withCC() {}
  withCC(const withCC&) {
    cout << "withCC(withCC&)" << endl;
  }
};

class woCC { // Without copy-constructor
  enum { bsz = 30 };
  char buf[bsz];
public:
  woCC(const char* msg = 0 ) {
    memset(buf, 0, bsz);
    if(msg) strncpy(buf, msg, bsz);
  }
  void print(const char* msg = 0) const {
    if(msg) cout << msg << ": ";
    cout << buf << endl;
  }
};

class composite {
  withCC WITHCC; // Embedded objects
  woCC WOCC;
public:
  composite() : WOCC("composite()") {}
  void print(const char* msg = 0) {
    WOCC.print(msg);
  }
};

main() {
  composite c;
  c.print("contents of c");
  cout << "calling composite copy-constructor"
       << endl;
  composite c2 = c;  // Calls copy-constructor
  c2.print("contents of c2");
}