Question

How do I define a typedef for a fixed length array so that I can also ‘new’. The following does not work:

typedef double Vector[3];
Vector *v = new Vector; // does not compile

We are trying to wrap into C++ some old C code which handles float * and float (*)[3] in a generic way.

Answer 1

The pointer to an double[3] is double * – so this will work:

  typedef double Vector[3];
  double *v = new Vector;

But I suggest you don’t use it that way – to delete the array you need the array-delete-operator:

  delete[] v;

But on new Vector you don’t see it is an array and so it might be forgotten.

This case is handled (and strongly recommended to avoid) in Scott Meyers Effective C++. So better don’t use an typedef here.