www.gusucode.com > C++ Primer 书籍源代码源码程序 > C++ Primer 书籍源代码源码程序/code/7/conv-enums.cpp
//Download by http://www.NewXing.com /* * 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 ""; }