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C++ Cookbook
book

C++ Cookbook

by D. Ryan Stephens, Christopher Diggins, Jonathan Turkanis, Jeff Cogswell
November 2005
Beginner to intermediate content levelBeginner to intermediate
594 pages
16h 23m
English
O'Reilly Media, Inc.
Content preview from C++ Cookbook

10.4. Making a Class Writable to a Stream

Problem

You have to write a class to an output stream, either for human readability or persistent storage, i.e., serialization.

Solution

Overload operator<< to write the appropriate data members to the stream. Example 10-6 shows how.

Example 10-6. Writing objects to a stream

#include <iostream> #include <string> using namespace std; class Employer { friend ostream& operator<< // This has to be a friend (ostream& out, const Employer& empr); // so it can access non- public: // public members Employer() {} ~Employer() {} void setName(const string& name) {name_ = name;} private: string name_; }; class Employee { friend ostream& operator<< (ostream& out, const Employee& obj); public: Employee() : empr_(NULL) {} ~Employee() {if (empr_) delete empr_;} void setFirstName(const string& name) {firstName_ = name;} void setLastName(const string& name) {lastName_ = name;} void setEmployer(Employer& empr) {empr_ = &empr;} const Employer* getEmployer() const {return(empr_);} private: string firstName_; string lastName_; Employer* empr_; }; // Allow us to send Employer objects to an ostream... ostream& operator<<(ostream& out, const Employer& empr) { out << empr.name_ << endl; return(out); } // Allow us to send Employee objects to an ostream... ostream& operator<<(ostream& out, const Employee& emp) { out << emp.firstName_ << endl; out << emp.lastName_ << endl; if (emp.empr_) out << *emp.empr_ << endl; return(out); } int main() { Employee emp; string first = ...
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Publisher Resources

ISBN: 0596007612Supplemental ContentErrata Page