deque学习之删除操作clear, erase, pop_front, pop_back, shrink_to_fit

本篇学习deque删除操作相关的函数

clear：清除内容

erase：擦除元素

pop_front：移除首元素

pop_back：移除末尾元素

shrink_to_fit：通过释放未使用的内存减少内存的使用

代码实现

#include <deque>
#include <iostream>
#include <time.h>

using namespace std;

class Person3
{

public:
    Person3(string name):
        m_strName(name)
    {

    }

    string m_strName;
};

void deleteElement()
{
    deque<Person3> deque1;
    string strName =  "《从军行(王昌龄)》青海长云暗雪山，孤城遥望玉门关。黄沙百战穿金甲，不破楼兰终不还！";

    //int = [-2147483648, 2147483647]
    const int count = 214748;//2147483648

    double startTime1 = clock();//1计算开始
    for(int i = 0; i < count; i++)//214748
    {
        deque1.emplace_back(strName);
    }
    double endTime1 = clock();//1时间结束
    cout << "deque1.size=" << deque1.size() << " deque1.max_size=" << deque1.max_size() << endl;
    deque1.clear();
    cout << "for    1 run time is: " << (double)(endTime1 - startTime1) / CLOCKS_PER_SEC << "s" << endl;
    cout << endl;

    deque<int> deque3;
    for(int i = 0; i < 11; i++)//214748
    {
        deque3.emplace_back(i);
    }
    cout << "deque3.size=" << deque3.size() << " deque3.max_size=" << deque3.max_size() << endl;
    for(auto &val: deque3)
    {
        cout << val << "\t";
    }
    cout << endl;
    deque3.pop_back();//移除尾部元素
    for(auto &val: deque3)
    {
        cout << val << "\t";
    }
    cout << endl;
    deque3.pop_front();//移除首部元素
    for(auto &val: deque3)
    {
        cout << val << "\t";
    }
    cout << endl;

    deque3.erase(deque3.begin() + 1);//删除deque3的第2个位置的元素
    for(auto &val: deque3)
    {
        cout << val << "\t";
    }
    cout << endl;
    deque3.erase(deque3.begin() + 2, deque3.end() - 1);//删除deque3的第3个位置到倒数第2个位置的元素
    for(auto &val: deque3)
    {
        cout << val << "\t";
    }
    cout << endl;
    cout << "deque3.size = " << deque3.size() << endl;
    deque3.shrink_to_fit();
    cout << "deque3.size = " << deque3.size() << endl;
    deque3.resize(10);
    cout << "deque3.size = " << deque3.size() << endl;
    deque3.shrink_to_fit();
    cout << "deque3.size = " << deque3.size() << endl;
    deque3.clear();
    cout << "deque3.size = " << deque3.size() << endl;
    cout << endl;
}

int main()
{
    deleteElement();
    cout << endl;

    cout << "Hello World!" << endl;
    return 0;
}

运行结果：

clear();//移除容器的所有数据

erase(beg,end);//删除[beg,end)区间的数据，返回下一个数据的位置。

erase(pos);//删除pos位置的数据，返回下一个数据的位置。

参考：

https://zh.cppreference.com/w/cpp/container/deque