Re: [Tinycc-devel] Tinycc issues

[Henrik Nordstrom]

On Tue, 15 Mar 2005, Dominic Mazzoni wrote:

> > > 2. Forward-declare arrays:
> > >   With gcc, I am allowed to forward-declare an array of unspecified size,
> > >   and then actually specify the size (implicitly) later in the code.  For
> > >   example:
> > >     int g_primes[];
> > >     ...
> > >     int g_primes[] = {2, 3, 5, 7, 11, 13, 17, 23};
> >
> > Why would one do this?
>
> Simple example: I want to define the array in a header file, but initialize 
> it in a C file.  I don't want to prespecify the number of elements in the 
> array because it's something that changes often, and I want to be able to 
> change it without recompiling any other C files.

For this you should forward declare the existence of the array, not the 
array as such...

extern/static int g_primes[];

...

int g_primes[] = {2, 3, 5, 7, 11, 13, 17, 23};


This assumes the array is at global or file scope, which is about the only 
situation where this kind of declarations makes sense. In local scope you 
better rearrange the code to have the definition in the proper place 
avoiding the need of forward declaration.

In your specific example with function pointers you can also solve the 
problem by forward declaring the functions you want to include in the 
array rather than the array. IMHO In many cases this also makes thre code 
more readable.

Regards
Henrik