How is the list used in C++?

In C++, a list is a type of container that uses a doubly linked list to store a collection of elements. It is one of the containers provided by the Standard Template Library (STL), located in the header file.

Characteristics of the list container include:

1. A doubly-linked list structure: each element contains pointers to the previous and next elements, allowing for constant time insertion and deletion at any position.
2. Random access is not supported: elements can only be accessed sequentially through iterators, and cannot be accessed directly by index like arrays.
3. Dynamic size: can increase or decrease dynamically based on needs.
4. Discontinuous storage: Elements are not stored in memory in a contiguous manner, but rather connected together through pointers.

In order to use the list container, you need to include the header file and define a list object using std::list. For example:

#include <list>

int main() {
    std::list<int> myList; // 定义一个存储int类型元素的列表

    // 向列表中添加元素
    myList.push_back(10);
    myList.push_back(20);
    myList.push_back(30);

    // 遍历列表并输出元素
    for (const auto& item : myList) {
        std::cout << item << " ";
    }
    std::cout << std::endl;

    return 0;
}

The above code demonstrates how to create a list object, add elements to it, and iterate through the elements in the list.

In addition to the push_back function, the list also offers other commonly used member functions such as push_front (to add elements to the beginning of the list), pop_back (to remove elements from the end of the list), pop_front (to remove elements from the beginning of the list), insert (to insert elements at a specified position), and erase (to delete elements at a specified position).

In conclusion, the list container is a dynamic-size, double-linked list structure container suitable for scenarios where frequent insertion and deletion of elements are needed, but not suitable for situations where random access to elements is required.