Question

i created a two dimensional matrix class which holds my object complex number.

I am trying to overload the parenthesis () so that I can access and modify the value at specified location of the matrix. say matrix[a][b]

= 5;

and my_vals is a private member of the matrix class. What is the problem with my code

//constructor & inlitilize dynamic array
matrix::matrix(int rows, int cols) {

complex** m_vals = new complex * [rows];
for (int i = 0; i < rows; ++i) {
m_vals[i] = new complex[cols];
}
// clean up and free the memory
for (int i = 0; i < rows; ++i) {
delete[]m_vals[i];
}
delete[]m_vals;
}

complex& operator()(int rows, int cols) {
return m_vals[rows][cols];
  

Answer 1

//constructor & inlitilize dynamic array
matrix::matrix(int rows, int cols) {
   // don't define m_vals as local variable as it is private member of the class matrix (complex **m_vals)
   m_vals = new complex *[rows];
   for (int i = 0; i < rows; ++i) {
       m_vals[i] = new complex[cols];
   }
  
   // no need to deallocate the matrix allocated
}

// define the below function in the matrix class

// overload subscript operator
// returns complex* when called for the first index i.e row since each row entry contains an array
// and when called for second index i.e column, returns the reference to the element
// to invoke this you need to use m[2][3] = 5;
// where m is of matrix object and 2 and 3 are index corresponding to row and column
// the above statement sets 5 to matrix entry of where row index = 2 and column index = 3
// index called must be valid.
complex *& operator[](int index){
return m_vals[index];
}

// overloading parenthesis operator

// returns the reference to the element at given indices
// to invoke this you need to use m(2,3) = 5;
// where m is of matrix object and 2 and 3 are index corresponding to row and column
// the above statement sets 5 to matrix entry of where row index = 2 and column index = 3
complex& operator()(int rows, int cols) {
return m_vals[rows][cols];
}