Storing pointers in multi-dimensional array

Question

My intention is to create a dynamic 3D array in C++ using pointers.

MyType*** myArray;
myArray = new MyType**[GRID_SIZE];
for (int i = 0; i < GRID_SIZE; ++i) {
  myArray[i] = new MyType*[GRID_SIZE];
  for (int j = 0; j < GRID_SIZE; ++j) {
    myArray[i][j] = new MyType[GRID_SIZE];
  }
}

Now this 3D array is ready to store MyType instances. What is the correct syntax needed when declaring this array if I want to store pointers to MyType instead of just MyType objects in this array?

IMO, this is poor idea. See the code in: http://stackoverflow.com/questions/2216017/dynamical-two-dimension-array-according-to-input/2216055#2216055 for an alternative. — Jerry Coffin, Feb 05 '11 at 23:22
In C++, you should almost always prefer the safety of `std::vector` to manually managing memory. — Seth Johnson, Feb 05 '11 at 23:24
@SethJohnson I agree wholeheartedly, but I'm modifying old code and rewriting everything is not an option. — sdfqwerqaz1, Feb 06 '11 at 14:31
@sdfq: You're clearly trying to write your "dynamic 3D array" from scratch, for which you should use `std::vector`. If something else in your program absolutely needs a pointer to an array of floats, then you could perhaps pass it `&(innervec.front())` while making sure that your `vector > > >` isn't destroyed. — Seth Johnson, Feb 06 '11 at 16:51
@SethJohnson I am replacing an existing array allocated on the stack with this version allocated on the heap. I will try using std::vector instead. — sdfqwerqaz1, Feb 06 '11 at 18:59

score 3 · Accepted Answer · answered Feb 05 '11 at 23:22

3

Simply add another * to your declaration, but don't call new on it.

answered Feb 05 '11 at 23:22

BlackBear

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I was of course absolutely sure that I had done that and that it didn't work. Well, I tried again and now it worked so I was obviously doing something crazy the first time. This is my dumbest question to date. I'll go and stand in the corner now. – sdfqwerqaz1 Feb 06 '11 at 12:01
@sdfqwerqaz: pointers are a mess. Me neither was sure it would work.. ;) – BlackBear Feb 06 '11 at 12:29

Storing pointers in multi-dimensional array

1 Answers1