C++ In a Nutshell

Boost

The Boost project was started by members of the C++ Standard Committee as a way to explore future directions for the C++ library and to provide a high-quality library that extends what is available in the standard C++ library. Boost has grown to encompass many areas, such as dates and times, regular expressions, lambda expressions, mathematical functions, graphs (the mathematical kind, not the pictorial kind), type traits, multithreaded programming, and more.

Some of the Boost packages have already been proposed as extensions to the standard library. By the time you read this, the Standard Committee might already have accepted a formal Technical Specification for an extension to the standard library. See my web site at http://www.tempest-sw.com/cpp/ for current information.

This section presents two of the packages in Boost that are part of the proposed library extension: tuples and smart pointers. A tuple is a generalization of the standard pair class template. Instead of being limited to 2 elements, a tuple can contain up to 10 elements (and the maximum can be extended if necessary). Example B-2 shows one way to use boost::tuple.

Example B-2. Using a tuple

#include <numeric>
#include <iostream>
#include <ostream>
#include <vector>
#include "boost/tuple/tuple.hpp"

// Store count, sum, and sum of squares.typedef boost::tuple<std::size_t, double, double> Stats;

// Accumulate statistics.
Stats stats(Stats s, double x)
{
 ++s.get<0>( ); s.get<1>( ) += x; s.get<2>( ) += x * x; return ...