何为set

set是STL中的一种关联容器，里面的元素根据关键字存储。set的元素都是唯一的，没有重复元素，我们可以利用这个特点进行去重的操作；

set中常用的方法

示例程序

void TestSet()
{
    // use constructor
    std::set<std::string> name;
    name.insert("Alex");
    name.insert("Alice");
    // delete duplicate element
    name.insert("Alex");
    std::cout << "size of name is " << name.size() << std::endl;

    for (std::string val : name)
        std::cout << val << "\t";
    std::cout << std::endl;

    // use erase to remove some element
    std::set<int> nums = { 1,2,3,4,5,6,7,8,9,10 };
    std::set<int> copynums(nums.find(4), nums.end());

    for (auto itr = nums.begin(); itr != nums.end(); )
    {
        if (*itr % 2 == 0)
        {
            itr = nums.erase(itr);
        }
        else
        {
            ++itr;
        }
    }

    for (const auto& val : nums)
    {
        std::cout << val << "\t";
    }
    std::cout << std::endl;

    copynums.erase(copynums.find(7), copynums.end());
    for (const auto& val : copynums)
    {
        std::cout << val << "\t";
    }
    std::cout << std::endl;

    std::cout << copynums.count(4) << std::endl;

    // checks if there is an element in the container and contains func exist in C++20 version
    /*if (money.contains(100))
    {
        std::cout << "100 is in this container" << std::endl;
    }
    else
    {
        std::cout << "100 is not in this container" << std::endl;
    }*/
}

程序输出结果

size of name is 2
Alex    Alice
1       3       5       7       9
4       5       6
1