引发异常：访问冲突读取位置0xCCCCCCCC

Question

我是C ++的初学者。
我应该制作输出形状区域的程序。

例如，

Input 1. Square  
Input 2. Rectangle  
Input 3. Circle  
Input 4. Print all the areas

User input: 1

Please give me the side.

The side is: 3

User input: 4

Square area: 9

//////////////////////////////////////////////////////

但是存在引发异常的问题。

我不知道为什么编译器会指出这一点。
有人可以解释吗？

source.cpp：

using namespace std;

int main() {        
    const int n = 10;
    Shape * arr[n];

    int input, index = 0;

    do
    {
        cout << "What shape that you want to create?" << endl;
        cout << "Input 1. Square \n";
        cout << "Input 2. Rectangle \n";
        cout << "Input 3. Circle \n";
        cout << "Input 4. Print all the areas \n";
        cout << "Input -1. Exit \n";

        cout << "User input: ";
        cin >> input;

        //Use switch statement to check user's input
        switch (input)
        {
        case -1:
            cout << "You inputted number : -1 \n" << "The program will be ended. " << endl;
            break;
        case 1:
            double side;
            cout << "Please give me the side: ";
            cin >> side;

            arr[index] = new Square(side);
            index++;
            break;
        case 2:
            double width, length;
            cout << "Please give me the width and length \n";
            cout << "Width is: ";
            cin >> width;
            cout << "Length is: ";
            cin >> length;

            arr[index] = new Rectangle(width, length);
            index++;
            break;
        case 3:
            double radius;
            cout << "Please give me the radius: ";
            cin >> radius;

            arr[index] = new Circle(radius);
            index++;
            break;
        case 4:
            for (int i = 0; i < 10; i++)
            {
                cout << arr[i]->getName();
                cout << " area: ";

                cout << fixed << showpoint <<
                    setprecision(2);

                cout << arr[i]->area() << endl;
            }
            break;
        default:
            cout << "You entered different number mentioned above!" << endl;
        }
    } while (input != -1);

    delete[] arr;

    system("pause");
    return 0;
}

编译器显示Project.exe中的0x0130C213引发了异常：0xC0000005：访问冲突读取位置0xCCCCCCCC。

我不明白为什么编译器会显示这个。

请给我任何建议！