main.cpp

# include<iostream>
# include"Square_Matrix.h" 
using namespace std;

 
int main()
{
    Square_Matrix a;
    a.Set_Size(3);
    a.Set_Elem(9,2,2);
         
    return 0; 
} 

Square_Matrix.h

# ifndef SQUARE_MATRIX_H
# define SQUARE_MATRIX_H
# include <iostream>
using namespace std;

class Square_Matrix
{
      private:
              int new_size = 0;
              int new_value = 0;
              int num_row = 0;
              int num_column = 0; 
              int **matrix;
               
      public:
             Square_Matrix();
             void Set_Size(const int new_size); // user set size of array 
             int Get_Size() const; // back work // creat array 
             void Set_Elem(const int new_value, int num_row, int num_column); //user use // give num for target space 
             int Get_Elem(int num_row, int num_column) const; // back work // set target space in array 
             void operator= (Square_Matrix rh); 
             ~Square_Matrix();  
}; 
# endif /* SQUARE_MATRIX_H */


Square_Matrix.cpp

# include "Square_Matrix.h"
# include <iostream>
using namespace std;

Square_Matrix::Square_Matrix()
{
              *matrix = new int [new_size];
      }; 
 
void Square_Matrix::Set_Size(const int new_size)
{ 
     this -> new_size = new_size; 
     }; 

int Square_Matrix::Get_Size() const 
{
    return matrix[new_size][new_size];
    }; 
    
void Square_Matrix::Set_Elem(const int new_value, int num_row, int num_column)
{          
     matrix[num_row][num_column] = new_value;
     cout << matrix [num_row][num_column] << endl; 
     };
     
int Square_Matrix::Get_Elem(int num_row, int num_column) const 
{
    return num_row, num_column; 
    }; 

Square_Matrix::~Square_Matrix()
{
    delete [] *matrix;
}

Line 27: error: Square_Matrix.h: No such file or directory
Line 1: error: expected constructor, destructor, or type conversion before '.' token
compilation terminated due to -Wfatal-errors.