conv-enums.cpp
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上传日期:2022-06-29
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书籍源码
开发平台:
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
- */
- /* Note: This code is an example of *bad* style and serves
- * only to illustrate the issues involved:
- *
- * First: overloading between int and unsigned often leads to ambiguities
- * Second: relying on the promotion type of an enumeration to determine
- * which function is matched is inherently machine-dependent.
- * A better design would include a specific 'format' function that took
- * an argument of type 'e2'
- */
- #include <string>
- using std::string;
- enum e1 {a1, b1, c1};
- enum e2 {a2, b2, c2=0x80000000};
- string format(int);
- string format(unsigned int);
- enum Stat {Fail, Pass};
- void ff(int);
- void ff(char);
- int main() {
- // ok: enumeration constant Pass promoted to int
- ff(Pass); // ff(int)
- ff(0); // ff(int)
- void ff(Stat);
- ff(Fail); // ff(Stat)
- string s1 = format(a1); // calls format(int)
- string s2 = format(a2); // calls format(unsigned int)
- return 0;
- }
- #include <iostream>
- using std::cout; using std::endl;
- void ff(int) { cout << "ff(int)" << endl; }
- void ff(char) { cout << "ff(char)" << endl; }
- void ff(Stat) { cout << "ff(Stat)" << endl; }
- string format(int) { cout << "format(int)" << endl; return ""; }
- string format(unsigned int) { cout << "format(unsigned int)" << endl;
- return ""; }