Boost C++ Libraries of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is the documentation for an old version of Boost. Click here to view this page for the latest version.


// Copyright (C) 2009-2012 Lorenzo Caminiti
// Distributed under the Boost Software License, Version 1.0
// (see accompanying file LICENSE_1_0.txt or a copy at
// Home at

#include <boost/detail/lightweight_test.hpp>
#include <algorithm>

// Unfortunately, cannot be defined locally (so not a real alternative).
struct global_add { // Unfortunately, boilerplate code to program the class.
    global_add(int& _sum, int _factor): sum(_sum), factor(_factor) {}

    inline void operator()(int num) { // Body uses C++ statement syntax.
        sum += factor * num;

private: // Unfortunately, cannot bind so repeat variable types.
    int& sum; // Access `sum` by reference.
    const int factor; // Make `factor` constant.

int main(void) {
    int sum = 0, factor = 10;

    global_add add(sum, factor);

    int nums[] = {2, 3};
    std::for_each(nums, nums + 2, add); // Passed as template parameter.

    BOOST_TEST(sum == 60);
    return boost::report_errors();