use-handle.cpp
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上传日期:2022-06-29
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书籍源码
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Visual C++
- /*
- * This file contains code from "C++ Primer, Fourth Edition", by Stanley B.
- * Lippman, Jose Lajoie, and Barbara E. Moo, and is covered under the
- * copyright and warranty notices given in that book:
- *
- * "Copyright (c) 2005 by Objectwrite, Inc., Jose Lajoie, and Barbara E. Moo."
- *
- *
- * "The authors and publisher have taken care in the preparation of this book,
- * but make no expressed or implied warranty of any kind and assume no
- * responsibility for errors or omissions. No liability is assumed for
- * incidental or consequential damages in connection with or arising out of the
- * use of the information or programs contained herein."
- *
- * Permission is granted for this code to be used for educational purposes in
- * association with the book, given proper citation if and when posted or
- * reproduced.Any commercial use of this code requires the explicit written
- * permission of the publisher, Addison-Wesley Professional, a division of
- * Pearson Education, Inc. Send your request for permission, stating clearly
- * what code you would like to use, and in what specific way, to the following
- * address:
- *
- * Pearson Education, Inc.
- * Rights and Contracts Department
- * 75 Arlington Street, Suite 300
- * Boston, MA 02216
- * Fax: (617) 848-7047
- */
- #include <iostream>
- using std::cout; using std::endl;
- #include "Handle.h"
- int main()
- {
- { // new scope
- // user allocates but must not delete the object to which the Handle is attached
- Handle<int> hp(new int(42));
- { // new scope
- Handle<int> hp2 = hp; // copies pointer; use count incremented
- cout << *hp << " " << *hp2 << endl; // prints 42 42
- *hp2 = 10; // changes value of shared underlying int
- } // hp2 goes out of scope; use count is decremented
- cout << *hp << endl; // prints 10
- } // hp goes out of scope; its destructor deletes the int
- }