Book Image

Boost C++ Application Development Cookbook - Second Edition

By : Anton Polukhin Alekseevic
Book Image

Boost C++ Application Development Cookbook - Second Edition

By: Anton Polukhin Alekseevic

Overview of this book

If you want to take advantage of the real power of Boost and C++ and avoid the confusion about which library to use in which situation, then this book is for you. Beginning with the basics of Boost C++, you will move on to learn how the Boost libraries simplify application development. You will learn to convert data such as string to numbers, numbers to string, numbers to numbers and more. Managing resources will become a piece of cake. You’ll see what kind of work can be done at compile time and what Boost containers can do. You will learn everything for the development of high quality fast and portable applications. Write a program once and then you can use it on Linux, Windows, MacOS, Android operating systems. From manipulating images to graphs, directories, timers, files, networking – everyone will find an interesting topic. Be sure that knowledge from this book won’t get outdated, as more and more Boost libraries become part of the C++ Standard.
Table of Contents (19 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Converting user-defined types to/from strings


There is a feature in Boost.LexicalCast that allows users to use their own types with lexical_cast. This feature requires from the user to write the correct std::ostream and std::istream operators for the type.

How to do it...

  1. All you need is to provide operator<< and operator>> stream operators. If your class is already streamable, nothing needs to be done:
#include <iostream>
#include <stdexcept>

// Negative number that does not store minus sign.
class negative_number {
    unsigned short number_; 

public:
    explicit negative_number(unsigned short number = 0)
        : number_(number)
    {} 

    // ...
    unsigned short value_without_sign() const {
        return number_;
    }
}; 

inline std::ostream&
    operator<<(std::ostream& os, const negative_number& num)
{
    os << '-' << num.value_without_sign();
    return os;
}

inline std::istream& operator>>(std::istream&amp...