C++ STD Gems02

remove、remove_if、replace、replace_if、remove_copy_if、unique

#include <iostream>

#include <string>

#include <iterator>

#include <vector>

#include <algorithm>

#include <cctype>

template<class Container>

void write_to_cout(const Container& container, const char* delimiter = " ")

{

    std::copy(container.begin(), container.end(),

        std::ostream_iterator<typename Container::value_type>(std::cout, delimiter) );

}

template<class Container, typename Pred>

void my_remove(Container& cont, Pred pred)

{

    const auto new_end = std::remove_if( cont.begin(), cont.end(), pred );     // 返回移除元素后新的迭代器位置，但容器容量大小并没有减少。

    cont.erase(new_end, cont.end());  // 后续处理

}

void test0()

{

    std::vector<std::string> a = {"zero", "one", "two", "three", "four", "five", "six", "seven"};

    //std::vector<std::string> b = {"0", "1", "2", "3", "4", "5", "6", "7"};

    write_to_cout(a);

    std::cout << std::endl;

    //write_to_cout(b);

    //std::cout << std::endl;

    //test algorithm

    // const auto new_end = std::remove_if(a.begin(), a.end(), [](std::string s)

    //         {

    //             return std::count(s.begin(), s.end(), 'o') == 0;

    //         }

    // );     // 返回移除元素后新的迭代器位置，但容器容量大小并没有减少。

    // a.erase(new_end, a.end());  // 后续处理

    //可以将上述操作封装成一个函数

    my_remove(a, [](std::string s){return std::count(s.begin(), s.end(), 'e') == 0;} ); //移除不含有字母e的单词

    write_to_cout(a, "|");

    std::cout << std::endl;

    std::cout << a.size() << std::endl;

}

void test1()

{

    std::vector<std::string> a = {"zero", "one", "two", "three", "four", "five", "six", "seven"};

    std::vector<std::string> b = {"0", "1", "2", "3", "4", "5", "6", "7"};

    write_to_cout(a);

    std::cout << std::endl;

    write_to_cout(b);

    std::cout << std::endl;

    //test algorithm

    //将容器a中的元素有条件地移除并复制到容易b中，但a中的元素并没有改变

    // 区分copy_if与remove_copy_if,他们唯一的不同之处在一个在copy时满足指定的谓词，另一个不满足明确的谓词

    std::remove_copy_if(a.begin(), a.end(), std::back_inserter(b), [](std::string s) {return std::count(s.begin(), s.end(), 'o') == 0;});

    write_to_cout(b);

    std::cout << std::endl;

    write_to_cout(a);

    std::cout << std::endl;

    std::cout << a.size() << std::endl;

    std::cout << std::endl << std::endl;

}

void test2()

{

    std::vector<std::string> a = {"zero", "one", "two", "three", "four", "five", "six", "seven"};

    std::vector<std::string> b = {"0", "1", "2", "3", "4", "5", "6", "7"};

    write_to_cout(a);

    std::cout << std::endl;

     write_to_cout(b);

     std::cout << std::endl;

    //test algorithm

    //测试一下remove_copy

    std::copy(a.begin(), a.begin() + 4, a.begin() + 3);

    std::remove_copy(b.begin(), b.begin() + 3, b.begin() + 3, "1");

    write_to_cout(a);

    std::cout << std::endl;

    write_to_cout(b);

    std::cout << std::endl << std::endl;

}

//replace_if

void test3()

{

    std::vector<std::string> a = {"zero", "one", "two", "three", "four", "five", "six", "seven"};

    write_to_cout(a);

    std::cout << std::endl;

    //test algorithm

    // 把容器中单词不含e的替换成11

    std::replace_if(a.begin(), a.end(), [](const std::string& s){return std::count(s.begin(), s.end(), 'e') == 0;}, "11");

    write_to_cout(a);

    std::cout << std::endl << std::endl;

}

void test4()

{

        std::vector<std::string> b = {"0", "1", "1", "2", "2", "2", "3", "4", "5", "6", "7",};

        write_to_cout(b);

        std::cout << std::endl;

        //test algorithm

        // 对于无序的容器，需要先排序

        auto new_end = std::unique(b.begin(), b.end()); // 去除重复元素

        write_to_cout(b);

        std::cout << std::endl;

}

int main()

{

    test0();

    test1();

    test2();

    test3();

    test4();

    return 0;

}
巴特西

C++ STD Gems02

remove、remove_if、replace、replace_if、remove_copy_if、unique

最新文章

热门文章
