Thread: new for 2D array

Code:

int **arry;
size_t ARRY_X = 3;
size_t ARRY_Y = 4;
    
arry = new int*[ARRY_X];
for(int i = 0; i < ARRY_X; i++)
   arry[i] = new int[ARRY_Y];

Originally Posted by Daved

Even better in C++:

Agreed, but it's worth it to know how to allocate multi-dimensional arrays.

On a side note...

Do you really want to make the spacial dimension dynamic? Because if you are only working with 2 and 3 dimensions (generally that is the case), I would advise against it. You are complicating your life as far as deallocation is concerned. Count how many deletes you have to write.

In fact, when working with multiple dimension dynamic arrays, the best option is to move to one dimensional arrays. Read http://www.parashift.com/c++-faq-lit...html#faq-16.16, taking into consideration that a multidimensional array is in fact an array of arrays, as Sly demonstrated.

However, better yet is to not make the spacial dimensions dynamic. Use typedefs to simplify your array usage. Like this:

Code:

typedef double koord_2D[2];
typedef double koord_3D[3];

koord_3D* Planet = new koord_3D[4];
koord_2D* Point = new koord_2D[4];

You have now two types that map to 2D and 3D spacial objects. Planets is an array of 4 planets on a 3D coordinates system. Points is an array of 4 points on a Cartesian coordinate system.

Any function can then use the typedef as a parameter and all will be much clearer.

EDIT: Oh! and the deletes... you just need two. One for Planet and one for Point

Boost.Multi_Array: http://boost.org/libs/multi_array/doc/index.html