迭代器

主要记录几种未注意到的迭代器，<= C++17.

  • istream_iterator

    std::vector<int> nums = {1, 2, 3, 4};
std::istream_iterator<int> input(std::cin);
std::copy(input, std::istream_iterator<int>(), std::back_inserter(nums));

  • ostream_iterator，格式化输出数组可以简单些

    std::vector<int> nums = {1, 2, 3, 4};
std::ostream_iterator<int> output(std::cout, " ");
std::copy(nums.begin(), nums.end(), output);

  • move_iterator

    std::vector<std::string> v{"this", "_", "is", "_", "an", "_", "example"};
std::string concat;
for (auto begin = std::make_move_iterator(v.begin()),
    end = std::make_move_iterator(v.end());
    begin != end; ++begin)
{
    std::string temp{*begin}; // moves the contents of *begin to temp
    concat += temp;
}

  • reverse_iterator

    在cbegin()和cend()之间反向迭代，迭代器++和–操作相比正常迭代器是反向的。

    std::vector<int> v = {1, 2, 3, 4, 5};
for (auto it = v.crbegin(); it != v.crend(); ++it)
{
    std::cout << *it << " ";
}

  • back_insert_iterator、front_insert_iterator、insert_iterator

    back_insert_iterator插入到容器的末尾，在一些algorithm库中有用，会自动调用push_back()。

    std::vector<int> v = {1, 2, 3, 4, 5};
std::vector<int> v2 = {6, 7, 8, 9, 10};
std::copy(v2.begin(), v2.end(), std::back_inserter(v));
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