请帮助我，因为我是编程新手，我制作了这个程序，对我来说不错，但是我得到的是垃圾值而不是两个矩阵的和。我应用了运算符重载的概念来求和两个矩阵，但是我一次又一次地获得垃圾值？请帮助我，问题出在哪里？谢谢。任何帮助都将受到感激

#include<iostream>
#include<string>

using namespace std;
class Matrix {
private:
    int matrix[2][2];
public:
    Matrix operator + (Matrix Sum)
    {
        Matrix sum[2][2];
        for (int i = 0; i < 2; i++)
        {
            for (int j = 0; j < 2; j++)
            {
                sum[i][j].matrix[i][j] = matrix[i][j] + Sum.matrix[i][j];
                return(sum[i][j]);
            }
        }
    }

    void setMatrix(int m[][2])
    {
        for (int i = 0; i < 2; i++)
        {
            for (int j = 0; j < 2; j++)
            {
                matrix[i][j] = m[i][j];
            }
        }
    }
    void Display() 
    {
          cout << "\n\nThe matrix finally equals: ";   
         for (int i = 0; i < 2; i++)
        {
            cout << " ";
            for (int j = 0; j < 2; j++)
            {
               cout<<matrix[i][j];
                if (j == 2 - 1)
                    cout << endl;
            }
        } 
    }
};


int main()
{
    Matrix m1,m2,sum;
   
    const int size=2;
    int matrix1[size][size];
    int matrix2[size][size];
    cout << "Enter the values of matrix 1 (2 X 2)\n\n";
    for (int i = 0; i < size; i++)
    {
        for (int j = 0; j < size; j++)
        {
            cin >> matrix1[i][j];
        }
    }

    cout << "Enter the values of matrix 2 (2 X 2)\n\n";
    for (int i = 0; i < size; i++)
    {
        for (int j = 0; j < size; j++)
        {
            cin >> matrix2[i][j];
        }
    }
    cout <<"\n\nSetting the values now\n\n";
    m1.setMatrix(matrix1);
    m2.setMatrix(matrix2);
    sum = m1 + m2;
    cout << "\n\nmatrix 1 (2 X 2) is : ";
    for (int i = 0; i < size; ++i)
    {
        for (int j = 0; j < size; ++j)
        {
            cout << matrix1[i][j] << "  ";
            if (j == size - 1)
                cout << endl;
        }
    }

    cout << "\n\nmatrix 2 (2 X 2) is : ";
    for (int i = 0; i < size; ++i)
    {
        for (int j = 0; j < size; ++j)
        {
            cout << matrix2[i][j] << "  ";
            if (j == size - 1)
                cout << endl;
        }
    }

    cout << "\n\nSum of two matrices is equal to (2 X 2) is : ";
    sum.Display();
    return 0;
}