为什么删除忽略删除除第一个以外的任何对象？

Question

我正试图在堆上创建4个学生对象。当我试图删除它们时，只有第一个被删除。

#include <iostream> 
using namespace std; 
class Student{ 
private: 
    int ID; 
    int score; 
public: 
    void setID(int num); 
    int getID(); 
    void setScore(int num); 
    int getScore(); 
}; 
void Student::setID(int num) 
{ 
    ID = num; 
} 
int Student::getID() 
{ 
    return ID; 
} 
void Student::setScore(int num) 
{ 
    score = num; 
} 
int Student::getScore() 
{ 
    return score; 
} 
class Creator 
{ 
public: 
    static int nextID; 
    Student* getObject(); 
}; 
int Creator::nextID = 0; 
Student* Creator::getObject() 
{ 
    Creator::nextID++; 
    Student* temp = new Student(); 
    temp->setID(Creator::nextID); 
    return temp; 
} 
int main() 
{ 
    Creator maker; 
    Student *pupil[4]; 
    int mark = 70; 
    for(std::size_t i = 0; i < (sizeof(pupil)/sizeof(pupil[0])); i++) 
    { 
     pupil[i] = maker.getObject(); 
     pupil[i]->setScore(mark); 
     mark += 10; 
    } 
    for(std::size_t i = 0; i < (sizeof(pupil)/sizeof(pupil[0])); i++) 
    { 
     cout<< "Sudent ID: "<<pupil[i]->getID()<<" has score of: "<<pupil[i]->getScore()<<endl; 
    } 
    //attempting to delete 
    for(std::size_t i = 0; i < (sizeof(pupil)/sizeof(pupil[0])); i++) 
    { 
     delete pupil[i]; 
    } 
    //confirm deletion 
    for(std::size_t i = 0; i < (sizeof(pupil)/sizeof(pupil[0])); i++) 
    { 
     cout<< "Sudent ID: "<<pupil[i]->getID()<<" has score of: "<<pupil[i]->getScore()<<endl; 
    } 
    return 0; 
} 

这里是输出：

Sudent ID: 1 has score of: 70 
Sudent ID: 2 has score of: 80 
Sudent ID: 3 has score of: 90 
Sudent ID: 4 has score of: 100 

删除后：

Sudent ID: 7864516 has score of: 7864516 
Sudent ID: 2 has score of: 80 
Sudent ID: 3 has score of: 90 
Sudent ID: 4 has score of: 100 

看起来好像只有第一个对象被删除，但其余的仍然存在。如何删除四个对象以避免内存泄漏？

Answer 1

当我尝试删除它们时，只删除第一个。

这是不正确的。实际上，您所有的Student都是delete d。你可以通过向Student添加一个析构函数来验证这一点，该析构函数在被调用时记录 - 你会看到它被调用4次。

这个误解来源于实际删除的意思。删除并不意味着内存被清零 - 只是它可供将来使用。实际上继续前进并将事情排除在外是浪费操作 - 通常不会发生。你在做什么 - 从已删除的内存读取数据 - 是未定义的行为。它看起来像以前的值，但它可能很容易为零。或随机垃圾。