What is the usage of the queue library in C++?

The queue library in C++ is used to implement a queue data structure. A queue is a data structure in which elements are arranged in the order they were added, following the First-In-First-Out (FIFO) principle, meaning elements can only be removed from the front and added to the back of the queue.

Here are examples of how to use the queue library:

1. Include the header file:

#include <queue>

1. Create a queue object:

std::queue<int> myQueue; // 创建一个存储int类型元素的队列

1. Addition and deletion of elements

myQueue.push(10); // 向队列尾部添加元素10
myQueue.push(20); // 向队列尾部添加元素20

myQueue.pop(); // 删除队列头部的元素

int frontElement = myQueue.front(); // 获取队列头部的元素
int backElement = myQueue.back(); // 获取队列尾部的元素

1. Check if the queue is empty.

if (myQueue.empty()) {
    // 队列为空
} else {
    // 队列不为空
}

In summary, the queue library provides a convenient way to implement a queue data structure, allowing for easy addition, removal, and access of elements in the queue, as well as determining if the queue is empty.