c++ - 使用继承重载 = 运算符

Question

嘿，我想了解如何在存在继承时重载 operator=没有成功。代码示例:

class Person 
{
    private:
            char* m_name;
            char* m_lastName;
    ..... 
    public:
            virtual Person& operator=(const Person& other);
};
/********************/
cpp implementation
/********************/
#include "Person.h"
Person& Person:: operator=(const Person& other)
{
     if(this == &other)
         return *this;
     delete[] m_name;
     delete[] m_lastName;
     if (other.m_name!=NULL)
     {
         m_name = new char[strlen (other.m_name)+1];
         strcpy(m_name,other.m_name);
     }
     if (other.m_lastName!=NULL)
     {
         m_lastName = new char[strlen (other.m_lastName)+1];
         strcpy(m_lastName,other.m_lastName);
     }
     return (*this);
}

现在假设 Student 从 Person 继承应该如何实现 = 运算符我认为它应该像下面这样请纠正我，因为我可能错了:

#include "Person.h"
class Student : public Person
{
    private:
            char* m_collageName;
    ..... 
    public:
            virtual Person& operator=(const Person& other);
};
/********************/
cpp implementation
/********************/
#include "Student.h"
Person& Student:: operator=(const Person& other)
{
     if(this == &other)
         return *this;
     Person::operator=(other);
     delete[] m_collage;
     if ((Student)other.m_collageName != NULL)
     {
        m_collageName = new char[strlen((Student)other.m_collageName)+1];
        strcpy(m_collageName,(Student)other.m_collageName);
     }
     return (*this);
}

非常感谢，非常感谢。

Answer 1

virtual 赋值运算符对我来说似乎是一种厌恶。赋值适用于值类型，而虚拟适用于多态类型。这两个几乎处于光谱的两端。

暂时想象一下这段代码:

void foo(person& x, const person& y)
{
  x = y;
}

另外我们还有这个

class teacher : public person {...};
class student : public person {...};

现在我们称它为:

teacher t;
student s;

foo(s,t);

那应该怎么办？把学生变成老师？为何如此？