#define ROW 3
#define COL 4
class Matrix
{
private:
int mat[ROW][COL];
//.....
//.....
};
int main()
{
Matrix m;
int a = m[0][1]; // reading
m[0][2] = m[1][1]; // writing
}
我认为直接不能超载[] [].
我想我必须间接地做,但如何实现它？
解决方法
更简单的解决方案是使用operator(),因为它允许多个参数.
class M
{
public:
int& operator()(int x,int y) {return at(x,y);}
// .. Stuff to hold data and implement at()
};
M a;
a(1,2) = 4;
简单的方法是第一个operator []返回一个中间对象,第二个operator []返回数组中的值.
class M
{
public:
class R
{
private:
friend class M; // Only M can create these objects.
R(M& parent,int row): m_parent(parent),m_row(row) {}
public:
int& operator[](int col) {return m_parent.at(m_row,col);}
private:
M& m_parent;
int m_row;
};
R operator[](int row) {return R(*this,row);}
// .. Stuff to hold data and implement at()
};
M b;
b[1][2] = 3; // This is shorthand for:
R row = b[1];
int& val = row[2];
val = 3;