动态分配类，存在继承问题
我正在尝试动态分配基（学生）类的数组，然后将指向派生（数学）类的指针分配给每个数组槽。我可以通过创建指向基类的单个指针，然后将其分配给派生类来使其工作，但是当我尝试将指针分配给动态分配的基类数组时，它会失败。我已经在下面发布了我正在使用的代码片段。所以基本上我的问题是，为什么动态分配的不工作？
Student* studentList = new Student[numStudents];
Math* temp = new Math(name, l, c, q, t1, t2, f);
studentList[0] = temp;
/*Fragment Above Gives Error:
main.cpp: In function âint main()â:
main.cpp:55: error: no match for âoperator=â in â* studentList = tempâ
grades.h:13: note: candidates are: Student& Student::operator=(const Student&)*/
Student * testptr;
Math * temp = new Math(name, l, c, q, t1, t2, f);
testptr = temp
//Works
I am trying to dynamically allocate an array of base(Student) classes, and then assign pointers to derived(Math) classes to each array slot. I can get it to work by creating a single pointer to the base class, and then assigning that to a derived class, but when I attempt to assign to the pointer to a dynamically allocated array of base classes, it fails. I have posted the fragments of code that I am using below. So basically my question is, why isn't the dynamically allocated one working?
Student* studentList = new Student[numStudents];
Math* temp = new Math(name, l, c, q, t1, t2, f);
studentList[0] = temp;
/*Fragment Above Gives Error:
main.cpp: In function âint main()â:
main.cpp:55: error: no match for âoperator=â in â* studentList = tempâ
grades.h:13: note: candidates are: Student& Student::operator=(const Student&)*/
Student * testptr;
Math * temp = new Math(name, l, c, q, t1, t2, f);
testptr = temp
//Works
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studentList[0]不是指针（即Student *），它是一个对象（即Student）。听起来有点像你需要的是一个指针数组。在这种情况下，您应该执行以下操作：
在此代码段中，
studentList的类型是Student **。因此，studentList[0]的类型为Student *。（请注意，在 C++ 中，有更好、更安全的方法来执行此操作，涉及容器类和智能指针。但是，这超出了问题的范围。）
studentList[0]is not a pointer (i.e. aStudent *), it's an object (i.e. aStudent).It sounds a bit like what you need is an array of pointers. In which case, you should do something like:
In this snippet, the type of
studentListisStudent **. Therefore, the type ofstudentList[0]isStudent *.(Note that in C++, there are better, safer ways to do this, involving container classes and smart pointers. However, that's beyond the scope of the question.)