C++ container adapter - queue (queue)

1 Introduction

queue is a container adapter that provides a queue function, and its data structure is FIFO (first-in, first-out) first- in-first -out ;

queue is a wrapper for the container deque;

header files and definitions

#include <queue>

template<
    class T,
    class Container = std::deque<T>
> class queue;

2. Initialization

queue cannot be initialized directly, but can be initialized by copying;

example

#include <iostream>
#include <queue>
#include <string>

using sstring = std::string;

int main(int argc, char* argv[])
{
    
    
    std::queue<sstring> que;
    que.push("c++");
    que.emplace("c");
    que.push("shell");
    que.emplace("Rust");

    std::queue<sstring> que1 = que;

    return 0;
}

3. use

Queue basic operations;

method	illustrate
operator=	assignment operation
front()	return the first element of the queue
back()	Returns the last element of the queue
empty()	Determine whether the queue is empty
size()	Return the size of the queue
push()	insert element
place()	Inserting elements is more efficient than push
pop()	Delete the element at the head of the queue
swap()	Exchange the elements of two queues

example

/*
 * @brief:    queue
 * @compile:  g++ -g queue_main.cc -o d -std=c++11
 * @author:   your name
 * @date:     2023/04/03
 * @lastEditorDate: 
 */

#include <iostream>
#include <queue>
#include <string>
#include <functional>

void printEnd(int32_t n){
    
    for(size_t i =0; i<n;i++) std::cout<<std::endl;}
std::function<void(int32_t)> e = printEnd;


using sstring = std::string;

int main(int argc, char* argv[])
{
    
    
    //front back empty size pop swap     

    //1.元素插入
    std::queue<sstring> que;
    que.push("c++");
    que.emplace("c");
    que.push("shell");
    que.emplace("Rust");
    que.emplace("linux");
    que.emplace("golang");  

    std::queue<sstring> que1 = que;  
    
    //2.元素遍历    
    std::cout<<"[que value] is: ";e(1);
    //pop()删除的是队首元素
    for(;!que.empty();que.pop())
    {
    
    
        std::cout<<que.front()<<" ";        
    }
    e(2);    

    //3.元素输出
    que = que1;    
    std::cout<<"front element value si: "<<que.front();e(1);
    std::cout<<"back element value si: "<<que.back();e(1);
    std::cout<<"size of que value si: "<<que.size();e(2);

    //4.元素的交换
    std::queue<sstring> que2;
    que2.swap(que1);
    if(que.empty())
    {
    
    
        std::cout<<"empty";e(1);
    }
    else{
    
    
        std::cout<<"not empty";e(1);
    }

    return 0;
}

output

[que value] is:
c++ c shell Rust linux golang

front element value si: c++
back element value si: golang
size of que value si: 6

not empty