queue-的常见操作

落日映苍穹つ 2022-06-07 00:11 208阅读 0赞

#include<iostream>
    #include <queue>
    #include <list>
    
    using namespace std;
    #if 0
    *   1.队列是一种容器适配器, 用于在FIFO上下文中进行操作, 其中元素从一段插入, 然后在另一端进行提取;
    *   2.队列实现为容器适配器, 使用特定容器类的封装对象作为其底层容器的类, 提供一些特定成员来访问其中的元素, 元素被推入特定容器的后面, 并且从容器的前面弹出;
    *   3.构造函数通常包括一下几种:
    *   1.explict queue(const container_type& ctnr)
    *   2.explict queue(container_type&& ctnr = container_type());
    *   3.template <class Alloc> explict queue(const Alloc& alloc);
    *   4.template <class Alloc> explict queue(const container_type& cntr, const Alloc& alloc);
    *   5.template <class Alloc> explict queue(container_type&& cntr, const Alloc &alloc);
    *   6.template <class Alloc> explict queue(const queue& X, const Alloc& alloc);
    *   7.template <class Alloc> explict queue(queue&& X, const Alloc& alloc);
    #endif
    
    int main()
    {
        //construct object;
        deque<int> mydeque(3, 33);
        list<int> mylist(2, 11);
    
        queue<int> first;
        first.push(3);
        queue<int> second(mydeque);
        queue<int, list<int>> third;
        queue<int, list<int>> fourth(mylist);
        cout << "first.size: " << first.size() << endl;
        cout << "second.size: " << second .size() << endl;
        cout << "third size: " << third.size() << endl;
        cout << "fourth.size: " << fourth.size() << endl;
    
        //.back():用于返回当前队列的最后一个元素;
        // reference& back();
        // const_reference& back() const;
        cout << "first.back: " << first.back() << endl;
    
    #if 1
        //.front()用于返回第一个元素
        //reference& front();
        //const_reference& front() const;
    
        first.front() += first.back();
        cout << "first.front: " << first.front() << endl;
    
        //.emplace(): template <class... args> void emplace(Args&&.. args)
        //用于在队列尾部添加一个新的元素;
    
        queue<string> myqueuestring;
        myqueuestring.emplace("this is a freshman");
        myqueuestring.emplace("this is a oldman");
        cout << "myqueuestring constains: ";
        while (!myqueuestring.empty())
        {
            cout << myqueuestring.front() << " ";
            myqueuestring.pop();
        }
        cout << endl;
        //.push用于在一段放入元素;
        //void push(const value_type& val);
        //void push(value_type&& val);
        myqueuestring.push("that is a no-name man");
        //.size()用于返回队列里面元素的多少;
    
        //.swap():用于交换两个队列的值;
        queue<int> newfirst;
        newfirst.push(1);
        newfirst.push(2);
        newfirst.push(3);
        newfirst.push(4);
        newfirst.push(5);
        queue<int> newsecond;
        newsecond.push(5);
        newsecond.push(4);
        newsecond.push(3);
        newsecond.push(2);
        newsecond.push(1);
    
        cout << "newfirst contains: ";
        while (!newfirst.empty())
        {
            cout << newfirst.front() << " ";
            newfirst.pop();
        }
        cout << endl;
        cout << "newsecond contains: ";
        while (!newsecond.empty())
        {
            cout << newsecond.front() << " ";
            newsecond.pop();
        }
        cout << endl;
    #endif
    
    }