I've been trying to create a variable length multidimensional array. As I understand, you can't create variable length arrays on the stack, but you can create 1D variable length arrays in C++ using dynamic allocation. Correct me if this is a compiler extension, but it seems to work fine on clang and gcc with --pedantic set.
int size = 10;
int *ary = new int[size]();
I tried to extend the concept to multidimensional arrays. Here are my results. The problem with possiblity 1 and 2 is that they require a constexpr and do not work with variable sizes. Is it possible to make either of them accept a variable as its size? I put possibility 3 as I am aware of it, but it lacks [][] access, which is what I'm looking for.
constexpr int constSize = 10;
//Possibility 1: Only works in C++11
//Creates CONTIGUOUS 2D array equivalent to array[n*n], but with [][] access
int (*ary1)[constSize] = new int[constSize][constSize]();
delete [] ary1;
//Possibility 2:
//Really horrible as it does NOT create a contiguous 2D array
//Instead creates n seperate arrays that are each themselves contiguous
//Also requires a lot of deletes, quite messy
int **ary2 = new int*[constSize];
for (int i = 0; i < n; ++i)
ary2[i] = new int[constSize];
for (int i = 0; i < n; ++i)
delete [] ary2;
delete [] ary2;
//Possibility 3:
//This DOES work with non-constexpr variable
//However it does not offer [][] access, need to access element using ary[i*n+j]
int *ary3 = new int[size*size];
delete [] ary3;