C++中对象的动态建立与释放详解及其作用介绍

int main() {
    
    Time *pt1 = new Time(8, 8, 8);
    pt1 -> show_time();

    delete pt1;  // 释放对象
    
    return 0;
}

#ifndef PROJECT1_BOX_H
#define PROJECT1_BOX_H

class Box {
public:
    // 成员对象
    double length;
    double width;
    double height;

    // 成员函数
    Box();  // 无参构造
    Box(double h, double w, double l);  // 有参有参构造
    ~Box();  // 析构函数
    double volume() const;  // 常成员函数
};

#endif //PROJECT1_BOX_H

#include <iostream>
#include "Box.h"
using namespace std;

Box::Box() : height(-1), width(-1), length(-1) {}

Box::Box(double h, double w, double l) : height(h), width(w), length(l) {
    cout << "========调用构造函数========\n";
}

double Box::volume() const{
    return (height * width * length);
}

Box::~Box() {
    cout << "========调用析构函数========\n";
}

#include "Box.h"
#include <iostream>
using namespace std;

int main() {

    Box *pt = new Box(16, 12, 10);  // 创建指针pt指向Box对象

    cout << "长:" << pt->length << "\t";
    cout << "宽:" << pt->width << "\t";
    cout << "高:" << pt->height << endl;
    cout << "体积:" << pt->volume() << endl;

    delete pt;  // 释放空间

    return 0;
}

const int N = 100;
Time t[N];

const int n = 3;  // 定义数组个数
Time *pt = new Time[n];  // 定义指针指向数组
delete []pt;  // 释放空间

int main() {

    const int n = 3;
    Time *t[n] = {nullptr};

    if (t[0] == nullptr){
        t[0] = new Time(8, 8, 8);
    }

    if (t[1] == nullptr){
        t[1] = new Time(6, 6, 6);
    }
    
    t[0] -> show_time();
    t[1] -> show_time();

    return 0;
}