包含二维2D数组的对象的重载赋值运算符

Question

我遇到了为下面的类编写重载赋值运算符的问题：

namespace w3{

    class DArray2d{

        int rows;
        int columns;
        double **array;

    public:

        DArray2d();
        DArray2d(int, int);
        DArray2d(const DArray2d &obj);
        DArray2d& operator=(DArray2d& rhs);
        DArray2d(const DArray2d &&obj);
        DArray2d& operator=(DArray2d&& rhs);
        double check() const;
        ~DArray2d();
    };

}

这是我尝试过的，但是我遇到了分段错误：11当我尝试复制for循环中的每个元素时：

w3::DArray2d& w3::DArray2d::operator=(w3::DArray2d& rhs){

    // std::cout << "assignment operator" << std::endl;

    if ( this != &rhs )
    {   


        this->rows = rhs.rows;
        this->columns = rhs.columns;

        std::cout << this->rows << std::endl;
        std::cout << this->columns << std::endl;

        for(int a = 0; a < rhs.rows; a++){
            for(int b = 0; b < rhs.columns; b++){
                array[a][b] = rhs.array[a][b];
            }
        }
    }

    return *this;

}

我有一个复制构造函数，我可以使用它吗？

w3::DArray2d::DArray2d( const DArray2d &obj):rows(obj.rows), columns (obj.columns) {

    // std::cout << "copy constructor" << std::endl;

    if(this != &obj){

        array = new double*[obj.rows];
        for(int i = 0; i < obj.columns; i++){
            array[i] = new double[columns];
        }

        for(int a = 0; a < obj.rows; a++){
            for(int b = 0; b < obj.columns; b++){
                array[a][b] = obj.array[a][b];
            }
        }

    }

}

另外，这是删除二维数组的正确方法吗？

for (int a = 0; a < rows ; ++a){
    delete [] array[a];
}
delete [] array;