STL中find的七大姑八大姨

//多次利用find查找出现的次数
    std::vector<int> numbers {5, 46, -5, -6, 23, 17, 5, 9, 6, 5};
    size_t count {};
    int five {5};
    auto start_iter = std::begin(numbers);
    auto end_iter = std::end(numbers);
    while((start_iter = std::find(start_iter, end_iter, five)) != end_iter)
    {
        ++count;
        ++start_iter;
    }
    std::cout << five << " was found " << count << " times." << std::endl;

  //find_if找到第一个大于5的元素
    int value {5};
    auto iter1 = std::find_if(std::begin(numbers), std::end(numbers),
                                    [value](int n) { return n > value; });
    if(iter1 != std::end(numbers))
        std::cout << *iter1 << " was found greater than " << value << ".\n";

//查找小于等于5的元素
    size_t count1 {};
    int five1 {5};
    auto start_iter1 = std::begin(numbers);
    auto end_iter1 = std::end(numbers);
    //当元素大于 five 时，才会返回 true
    while((start_iter1 = std::find_if_not(start_iter1, end_iter1,
                        [five1](int n) {return n > five1; })) != end_iter1)
    {
        ++count1;
        ++start_iter1;
    }
    std::cout << count1 << " elements were found that are not greater than "<< five1 << std::endl;

 // text 中查找第一次出现的 vowels 中的任意字符。在这个示例中，返回的迭代器指向“The”的第三个字母
    string text {"The world of searching"};
    string vowels {"aeiou"};
    auto iter = std::find_first_of (std::begin(text), std:: end(text),
                     std::begin(vowels),std::end(vowels));
    if(iter != std::end(text))
        std::cout << "We found '" << *iter << "'." << std::endl;

    //用循环来查找 text 中所有匹配 vowels 中字符的字符
    string found{}; 
    for(auto iter = std::begin(text);(iter = std::find_first_of (iter,std::end(text),
                    std::begin(vowels),std::end(vowels)))!= std::end(text);)
            found += *(iter++);
    std::cout << "The characters \"" << found << "\" were found in text." << std::endl;//"eooeai"

  // numbers 中第一个可以被 factors 数组中的元素 13 整除的元素
    std::vector<long> numbers2{64L, 46L, -65L, -128L, 121L, 17L, 35L, 9L, 91L, 5L};
    int factors[] {7, 11, 13};
    auto iter2 = std::find_first_of(std::begin(numbers2),std::end(numbers2),std::begin(factors),
    std::end(factors),[](long v, long d) { return v % d == 0; });
    if (iter2 != std::end (numbers2))
        std::cout << *iter2 << " was found." << std::endl;

//搜索 saying 字符串的前两个相等字符
    string saying{"Children should be seen and not heard."};
    auto iter3 = std::adjacent_find(std::begin(saying), std::end(saying));
    if (iter3 != std::end(saying))
        std::cout <<"In the following text: \n\""<< saying << "\"\n'"<< *iter3 << 
            "' is repeated starting at index position "<< std::distance(std::begin(saying), iter3) << std::endl;

//查找这个序列中第一对都为奇数的连续整数
    std::vector<long> numbers3{64L, 46L, -65L, -128L, 121L, 17L, 35L, 9L, 91L, 5L};
    auto iter4 = std::adjacent_find(std::begin(numbers3),std::end(numbers3),
                            [](long n1, long n2){ return n1 % 2 && n2 % 2; });
    if(iter4 != std::end(numbers3))
        std::cout <<"The first pair of odd numbers is "<< *iter4 << " and " << *(iter4+1) << std::endl;//121 17

//从 text 中搜索“had had”的最后一个匹配项
    string text{"Smith, where Jones had had \"had\", had had \"had had\"." "
                     \"Had had\" had had the examiners\' approval."};
    std::cout << text << std::endl;
    string phrase{"had had"};
    auto iter = std::find_end(std::begin(text), std::end(text), std::begin(phrase),std::end(phrase));
    if(iter != std::end(text))
    std::cout << "The last \"" << phrase<< "\" was found at index "<<
                 std::distance(std::begin (text), iter) << std::endl;

//循环表达式会在 [std::begin(text)，end_iter) 这个范围内搜索 phrase。最开始的搜索范围包含 text 中的全部元素
    size_t count2{};
    auto iter5 = std::end(text1);
    auto end_iter2 = iter5;
    while((iter5 = std::find_end(std::begin(text1), end_iter2, std::begin(phrase), std::end(phrase)))!= end_iter2)
    {
        ++count2;
        end_iter2 = iter5;
    }
    std::cout << "\n\""<< phrase << "\" was found " << count2 <<" times." << std::endl;

//在 text 中会找到与phrase相等 的 5 个实例，忽略大小写
    size_t count3 {};
    auto iter7 = std::end(text1);
    auto end_iter3 = iter7;
    while((iter = std::find_end(std::begin(text1), end_iter3, std::begin(phrase), std::end (phrase) ,
                [] (char ch1, char ch2) { return std::toupper (ch1) == std::toupper(ch2);})) != end_iter3)
    {
        ++count3;
        end_iter3 = iter7;
    }
     std::cout << "\n\""<< phrase << "\" was found " << count3 <<" times." << std::endl;

     //忽略大小写来搜索“had had”，但会正向查找第一个匹配项。search() 算法返回的迭代器指向找到的子序列的第一个元素
    string text2{"Smith, where Jones had had \"had\", had had \"had had\"."" \"Had had\" had had the examiners\' approval."};
    std::cout << text2 << std::endl;
    string phrase1{"had had"};
    size_t count4 {};
    auto iter8 = std::begin(text2);
    auto end_iter4 = end(text2);
    while((iter8 = std::search(iter8, end_iter4, std::begin(phrase1), std::end (phrase1) ,
            [](char ch1, char ch2) { return std::toupper (ch1) == std:: toupper (ch2); })) != end_iter4)
    {
        ++count4;
        //为了搜索 phrase 的第二个实例，iter 必须增加 phrase 中元素的个数，使它指向下一个找到的序列的第一个元素。
        std::advance(iter8, phrase1.size());
    }
    std::cout << "\n\""<< phrase1 << "\" was found "<< count4<< " times." << std::endl;

   std::vector<double> values{2.7, 2.7, 2.7, 3.14, 3.14, 3.14, 2.7, 2.7};
    double value1{3.14};
    int times {3};
    auto iter9 = std::search_n(std::begin(values), std::end(values), times, value1);
    if (iter9 != std::end(values))
        std::cout << times << " successive instances of " << value1<< 
                " found starting index " << std::distance (std::begin (values), iter9) <<std::endl;

  //一年中每个月份的平均温度
    std::vector<int> temperatures{65, 75, 56, 48, 31, 28, 32, 29, 40, 41, 44, 50};
    int max_temp{32};
    int times1 {3};
    //元素小于等于 max_temp 时，它会返回 true
    auto iter10 = std::search_n(std::begin(temperatures), std::end(temperatures), times1, max_temp,
            [](double v, double max){return v <= max; });
    std::vector<string> months {"January", "February", "March", "April", "May", "June","July",
            "August", "September", "October", "November", "December"};
    if(iter10 != std::end(temperatures))
    //distance返回 temperatures 这个序列的第一个元素的索引
        std::cout << "It was " << max_temp << " degrees or below for " << times1<< 
                " months starting in " << months[std::distance(std::begin(temperatures), iter10)]<< std::endl;