C/C++ performance of static arrays vs dynamic arrays

Question

When performance is essential to an application, should consideration be given whether to declare an array on the stack vs the heap? Allow me to outline why this question has co

Answer 1

As to which choice provides better performance, then the answer will largely depend on your specific circumstances. The only way to know if one way is better or if they are roughly equivalent is to measure the performance of your application.

Some things that would be a factor are: how often you do it, the actual size of the arrays/data, how much memory your system has, and how well your system manages memory.

If you have the luxury of being able to choose between the two choices, it must mean the sizes are already nailed up. Then, you do not need the multiple allocation scheme that you illustrated. You can perform a single dynamic allocation of your 2D array. In C:

int (*array)[COLUMNS];
array = malloc(ROWS * sizeof(*array));

In C++:

std::vector> array(ROWS);

As long as the COLUMNS is nailed down, you can perform a single allocation to obtain your 2D array. If neither are nailed down, then you don't really have the choice of using a static array anyway.