Implement class in C++, matrices

Question

C++ / C#

There are matrix programs (each separate) in C++, such as - addition / subtraction, multiplication, transposition, inverse matrix. We need to get them into the classroom.
With OOP, just started. But the finished class must be handed over in 3 days. Help to implement the class, at least a few lines on the design of the code (methods and their arguments (I can write the implementation of the method myself), etc.)
Please help.

Answer 1

#include <stdexcept>

using namespace std;

class Matrix
{
protected:
  double *matrix;
  unsigned size_x, size_y;
  
public:
  Matrix()
  {
    matrix = NULL;
    size_x = size_y = 0;
  }
  
  Matrix(unsigned sz_x, unsigned sz_y)
  {
    matrix = new double[sz_x * sz_y];
                            size_x = sz_x; size_y = sz_y;
  }
  
  /** Во всех операциях, где участвуют две матрицы нужно проверять их совместимость по размеру **/
  
  Matrix& operator+(Matrix &b)
  {
    
  }
  
  Matrix& operator-(Matrix &b)
  {
    
  }
  
  Matrix& operator*(Matrix &b)
  {
    
  }
  
  double* operator[](unsigned index)
  {
    if(index > sz_y)
      throw out_of_range("Index is out of range");
    
    return &matrix[index * sz_x];
  }
  
  Matrix& transpose()
  {
  
  }
  
  Matrix& reverse()
  {
  
  }
};

Regarding access to elements - the operator [] returns a row of the matrix, i.e. when accessing a matrix element - my_matrix[<row_number>][<column_number>], the first brackets return a piece of the array that starts with the required row (here the index is controlled), and the second - the element itself (here the index is not controlled). If you need full control - then a double array and a function double get(unsigned i, unsigned j) {}. If this is not so important, then you can do it as indicated.