删除此指针

Question

这是关于删除堆上分配的对象的指针.程序如下,

class Sample{
      private:
              int m_value1;
              int m_value2;

      public:
             Sample();
             void setValues(int m_value1, int m_value2);
             void display();
      };

Sample::Sample(){
                 this->m_value1 = 0;
                 this->m_value2 = 0;
                 }

void Sample::setValues(int m_value1, int m_value2){
     this->m_value1= m_value1;
     this->m_value2 = m_value2;
     display();
     if(this != NULL)
     {
             cout <<"Deleting this pointer!"<<endl;
             delete this;
             cout <<"this->m_value1 is "<<this->m_value1<<endl;
             cout <<"this->m_value2 is "<<this->m_value2<<endl;

     }
     }

void Sample::display(){
     cout <<"Values are "<<this->m_value1<<" and "<<this->m_value2<<endl;

     }

int main(){
    Sample *obj1 = new Sample();;
    obj1->setValues(4,6);
    obj1->display();
    getch();
}

OUTPUT:

Values are 4 and 6
Deleting this pointer!
this->m_value1 is 65535
this->m_value2 is 6
Values are 65535 and 6

为什么m_value1的值会消失,而另一个变量m_value2会保留？

Answer 1

在delete this未定义的行为之后访问成员变量- 任何事情都可能发生,包括读取意外数据,程序崩溃或其他任何事情.该对象已被销毁并取消分配,您尝试取消引用无效指针.一旦delete this发生 - 不要尝试访问成员变量,不要尝试调用成员函数,也不要做任何其他事情(包括比较或转换)到this指针.