global variables in C++

Question

So I have something like this

#define HASHSIZE 1010081

static struct nlist *hashtab[HASHSIZE];

Now I want to be able to change the HASHSIZE of my hashtab, because I want to test different primes numbers and see which would give me less collisions. But Arrays do not take variable sizes so HASHSIZE has to be a constant. Is there a way to go about this?

Answer 1

Why don't you use std::vector instead of using arrays in C++?

Eg:

  std::vector<nlist *> hashtab; 
  hashtab.resize(<some_value>); 

But anyways you can do this if you are using g++ because g++ supports Variable Length Arrays(VLAs) as an extension.

Eg:

  int HASHSIZE=<some_value>
  static struct nlist *hashtab[HASHSIZE];