C++ Overloading Assignment - Exercise

Here is the code for the matrix class:

class matrix {
public:
   matrix(int d);
   matrix(int d1, int d2);
   ~matrix();
   int ub1() const { return (s1 - 1); }
   int ub2() const { return (s2 - 1); }
private:
   int**   p;
   int     s1, s2;
};

matrix::matrix(int d): s1(d), s2(d)
{
   if (d < 1) {
      cerr << "illegal matrix size"
        << d << "by" << d << "\n";
      exit(1);
   }
   p = new int*[s1];
   for (int i = 0; i < s1; i++)
      p[i] = new int[s2];
}

matrix::matrix(int d1, int d2): s1(d1), s2(d2) {
  if (d1 < 1 || d2 < 1) { 
    cerr << "illegal matrix size" << d1 << "by" << d2 << "\n"; 
    exit(1); 
  } 
  p = new int*[s1]; 
  for (int i = 0; i < s1; i++) 
    p[i] = new int[s2]; 
} 
matrix::~matrix(){ 
  for (int i = 0; i <= ub1(); ++i) 
   delete p[i]; delete []p;
}

The code for the matrix class is available in a file named matrix.cpp, which can be found in the compressed course download file available on the Resources page. Paste your code below and click the Submit button when you are ready to submit this exercise.