复制动态阵列并使用过载的操作员删除原件

我正在创建一个可以跟踪学生的课程。在此课程中，我使用一个Overloaded =复制这些学生对象。要跟踪他们的课程，我使用一个动态数组。阵列的副本很好。但是，在清除学生对象的变量时，从之前复制的任何对象也都会擦拭数组。这是代码：

#include <iostream>
#include <string>
using namespace std;
class Student
{
    string name;                //Name
    string* classList = NULL;   //Empty array to store class names in
    int numClasses = 0;         //Number of classes
public:
    void InputData()
    {
        cout << "Enter student name: " << endl;                         //Input Name
        cin >> name;
        cout << "Enter number of classes: " << endl;                    //Input classes
        cin >> numClasses;
        classList = new string[numClasses];                             //Define array size
        for (int i = 0; i < numClasses; i++)                            //For every spot in array, name class
        {
            cout << "Enter name of class " << (i + 1) << ":" << endl;   //Name class
            cin >> classList[i];
        }
    };
    void OutputData()
    {
        cout << "Name: " << name << endl;                               //Output data
        cout << "Number of Classes: " << numClasses << endl;
        for (int i = 0; i < numClasses; i++)                            //Cycle through and output classes
        {
            cout << "Class " << i << ": " << classList[i] << endl;
        }
    };
    void ResetClasses()
    {
        name = "";
        delete[] classList;         //Free Memory
        classList = NULL;           //Clear array
        numClasses = 0;
    };
    Student operator =(Student& student)                //Overload =
    {
        this->name = student.name;
        this->classList = student.classList;
        this->numClasses = student.numClasses;
        return *this;
    };
};
int main()
{
    Student s1, s2;
    s1.InputData();               // Input data for student 1
    cout << "Student 1's data:" << endl;
    s1.OutputData();              // Output data for student 1
    s2 = s1;
    cout << "Student 2's data after assignment from student 1:" << endl;
    s2.OutputData();              // Should output same data as for student 1
    s1.ResetClasses();
    cout << "Student 1's data after reset:" << endl;
    s1.OutputData();              // Should have no classes
    cout << "Student 2's data, should still have original classes:" << endl;
    s2.OutputData();              // Should still have original classes
}

主要罪犯几乎可以肯定是这两个

        void ResetClasses()
        {
            name = "";
            delete[] classList;         //Free Memory
            classList = NULL;           //Clear array
            numClasses = 0;
        };
        Student operator =(Student& student)                //Overload =
        {
            this->name = student.name;
            this->classList = student.classList;
            this->numClasses = student.numClasses;
            return *this;
        };

程序的输出是：

Enter student name:
ERIC
Enter number of classes:
2
Enter name of class 1:
C++
Enter name of class 2:
C
Student 1's data:
Name: ERIC
Number of Classes: 2
Class 0: C++
Class 1: C
Student 2's data after assignment from student 1:
Name: ERIC
Number of Classes: 2
Class 0: C++
Class 1: C
Student 1's data after reset:
Name:
Number of Classes: 0
Student 2's data, should still have original classes:
Name: ERIC
Number of Classes: 2
Class 0:
Class 1:

造成这一点我会做什么？