How to overload array index operator for wrapper class of 2D array?
c++, operator-overloading
Solution
The easier solution is to use the operator() as it allows multiple parameters.
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;
The easy way is that the first operator[] returns an intermediate object that the second operator[] returns the value from the array.
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;
Problem
``` #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 } ``` I think directly it not possible to overload [][] . I think i have to do it indirectly but how to implement it?