Question

i do this in the education purpose.
such is idea:
i have class Array. I inheritance it in class Darray, and add necessary dimension

it likes so:

main.cpp

int main(int argc, char *argv[])
{


  Array obj;
  obj.output();

 DArray obj2;
 obj2.output();

   return 0;

}

header

      class Array

       {
        public:
          int  *x,sizem;  //одно измерение, массив
                // можно объявить здесь как  **x , но это не то

      Array();
       ~Array();
   virtual  void output();
   };


   class DArray:public Array
 {
public:
 int **z;
  int sizen;
   DArray();
~DArray();
 virtual void output();
};

realisation.cpp

           Array::Array()
        {
        sizem=5;

        x=new int[sizem];

         for(int i=0;i<sizem;i++)
       x[i]=i;
         }

        Array::~Array()
     {
        delete []x;
       }


       void Array::output()
       {
       for(int i=0;i<sizem;cout<<x[i]<<" ",i++);
       cout<<"\n";
        }


           void DArray::output()
      { cout<<"\n";

       for(int i=0;i<sizem;i++)
         {   for(int j=0;j<sizen;j++)
               cout<<z[i][j]<<" ";
             cout<<"\n";
              }
              }       


        DArray::DArray()
           {
            int i;
           sizen=sizem;

           z=new int*[sizem];   // одно измерение уже есть, т.е. это одна строка


             for(i=1;i<sizem;i++)
               z[i]=new int[sizem];


            for(int i=1;i<sizem;i++)   // if i don't initialization  matrix, all'll 

          works right,compiles,and run, but AFAIK  when i allocate space dynamically,
         it must be intitializationed self by zeros, but it isn't particually equal
          zeroes, the fisrt two  column are equal  some random number, other 
       are equal zero.


             for(int j=0;j<sizen;j++)
               {
                z[i][j]=2;
                }

              *z=x;  // i've already array x , that was inheritanced, just point address
            }



                DArray::~DArray()
           {


          for(int i=1;i<sizem;i++)
           delete z[i];


           // yet one problem 
           // i can't delete  x  e.g. delete []x
         // but it should work! 

                 delete []z;
                   }

PS I works without errors, but i think there are memory leak, but can’t catch up why

all tricks has been done in constructor, everything other is general stuff like output matrix/array. that’s why i think that problem is there

thanks you  mates!

but i don’t understand yet one thing

          z=new int*[sizem];  

           for(i=1;i<sizem;i++)
          z[i]=new int[sizem];


       for(int i=1;i<sizem;i++)
      {
         for(int j=0;j<sizen;j++)

           cout<<z[i][j]<< " ";
           cout<<"\n";
       }
 as i think i have to receive here  ones zeros. byt i receive something like

          2532336 2532336 0 0 0 
          2532336 2532336 0 0 0 
          2532336 2532336 0 0 0 
          2532336 2532336 0 0 0 

Why?

Answer 1

There are no memory leaks, but there is one mismatch between new and delete:

You’re using new[] here:

for(i=1;i<sizem;i++)
    z[i]=new int[sizem];

but you’re using delete (not delete[]) here:

for(int i=1;i<sizem;i++)
    delete z[i];

With that changed to delete[] z[i];, there are no warnings from valgrind:

==29235== HEAP SUMMARY:
==29235==     in use at exit: 0 bytes in 0 blocks
==29235==   total heap usage: 7 allocs, 7 frees, 160 bytes allocated
==29235== 
==29235== All heap blocks were freed -- no leaks are possible

EDIT: regarding your second question, if you want the arrays to be initialized with zeroes, use

z[i] = new int[sizem](); // note the pair of parentheses

or just use vectors like everybody else.