C++ STD Gems01

本文是根据油管大神的C++标准库课程的一个学习笔记，该课程主要介绍c++标准库中一些非常有用并且代码经常用到的工具。

copy 、copy_backward 、copy_n 、copy_if、swap_ranges

#include <iostream>
#include <iterator>
#include <string>
#include <algorithm>
#include <vector>
#include <cctype>

template<typename 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) );
}

// 测试函数copy
void test0()
{
    // init test constainer
    std::vector<std::string> a = {"zero", "one", "two", "three", "four", "five", "six"};
    std::vector<std::string> b = {"0", "1", "2", "4", "5", "6", "7", "8", "9"};

    // wtire initial statements
    write_to_cout(a);
    std::cout << std::endl;
    write_to_cout(b);
    std::cout << std::endl;

    //test algorithm
    std::copy(a.begin(), a.begin() + 3, b.begin() + 4);
    write_to_cout(b);
    std::cout << std::endl;
    std::cout << std::endl;
}

void test1()
{
    std::vector<std::string> a = {"zero", "one", "two", "three", "four", "five", "six"};
    std::vector<std::string> b = {"0", "1", "2", "4", "5", "6", "7", "8", "9"};

    write_to_cout(a);
    std::cout << std::endl;
    write_to_cout(b);
    std::cout << std::endl;

    std::copy(a.begin(), a.end(), std::back_inserter(b));
    write_to_cout(b);
    std::cout << std::endl;
    std::cout << std::endl;
}

void test2()
{
    // std::vector<std::string> a = {"zero", "one", "two", "three", "four", "five", "six"};
    std::vector<std::string> b = {"0", "1", "2", "4", "5", "6", "7", "8", "9"};

    // write_to_cout(a);
    // std::cout << std::endl;
    write_to_cout(b);
    std::cout << std::endl;

    // test algorithm
    std::copy(b.begin(), b.begin() + 4, b.begin() +3);  // 元素从前往后挨个复制过去
    write_to_cout(b);
    std::cout << std::endl;
    std::cout << std::endl;
}

void test3()
{
    std::vector<std::string> a = {"zero", "one", "two", "three", "four", "five", "six"};
    std::vector<std::string> b = {"0", "1", "2", "4", "5", "6", "7", "8", "9"};

    write_to_cout(a);
    std::cout << std::endl;
    write_to_cout(b);
    std::cout << std::endl;

    //test algorithm
    std::copy_backward(a.begin(), a.begin() + 2, b.begin() + 3); //从后往前挨个复制过去
    write_to_cout(b);
    std::cout << std::endl;
    std::cout << std::endl;
}

void test4()
{
    std::vector<int> a;
    std::copy_n(std::istream_iterator<int>(std::cin), 5, std::back_inserter(a)); // 输入指定的数量的元素
    write_to_cout(a);
    std::cout << std::endl;
    std::cout << std::endl;
}

void test5()
{
    std::string a = "HellO, WOrlD";
    std::string b = "wHat are yoU dOinG";

    write_to_cout(a);
    std::cout << std::endl;
    write_to_cout(b);
    std::cout << std::endl;

    //test algorithm
    std::string uppers;
    // 有条件地复制
    std::copy_if(a.begin(), a.end(), std::back_inserter(uppers), [](unsigned char c){return std::isupper(c);} );  // 为什么直接写std::isupper不行呢
    std::copy_if(b.begin(), b.end(), std::back_inserter(uppers), [](unsigned char c){return std::isupper(c);} );

    write_to_cout(uppers);
    std::cout << std::endl << std::endl;
}

void test6()
{
    std::vector<std::string> a = {"zero", "one", "two", "three", "four", "five", "six"};
    std::vector<std::string> b = {"0", "1", "2", "4", "5", "6", "7", "8", "9"};

    write_to_cout(a);
    std::cout << std::endl;
    write_to_cout(b);
    std::cout << std::endl;

    //test algorithm
    std::swap_ranges(a.begin(), a.begin() + 3, b.begin());  //作用于copy等效
    write_to_cout(b);
    std::cout << std::endl << std::endl;

}

int main()
{
    test0();
    test1();
    test2();
    test3();
    test4();
    test5();
    test6();
    return 0;
}