🚀 go-pugleaf

In article <Pine.A32.3.91.951127202934.29743A-100000@srv1.freenet.calgary.ab.ca> "Michael E. Wesolowski" <mewesolo@freenet.calgary.ab.ca> writes:
>I don't know if this is a problem with gcc, the DOS port of gcc, or 
>something (i.e., not a bug) in the implementation that I don't know 
>about. I'm using the DOS port of gcc (djgpp), v1.12m4. This is equivalent 
>ot gcc 2.6.3, if I remember correctly.
>
>I have a generic function which has as one of its input parameters an int 
>which identifies an array size. Within the function, I attempt to declare 
>an array of int's:
>
>int item_count [array_size];
>
>where array_size is the input parameter. When I look at the array in the 
>debugger (gdb) however, what i see is an array of int pointers (I think) 
>- something like int (*) [60000] (the 60000 is approximate). If I 
>explicitly declare the array as, for example, item_count [10], I get the 
>expected array of 10, uninitialized ints. SO, what's the problem?
>
>If it's something in the ANSI standard, I'd appreciate the paragraph 
>reference as well as a simple description of what's going on. Thanks.
>

If I understand you correctly, you're trying to do some sort of
dynamic allocation of an automatic array, e.g:

    void myfunc (int size)
    {
      int i, item[size];

      for (i=0; i<size; i++) item[i] = i;
    }

I don't think this is supported by ANSI C.
To obtain what you want, you can use malloc():

    void myfunc (int size)
    {
      int i, *item;

      item = (int *)malloc(size*sizeof(int));
      for (i=0; i<size; i++) item[i] = i;
      free (item);
    }

If you're programming in C++, you can use 'new' for this purpose.

Pieter Kunst (kunst@natlab.research.philips.com)

Hi,
"Michael E. Wesolowski" (mewesolo@freenet.calgary.ab.ca) wrote:
: I have a generic function which has as one of its input parameters an int 
: which identifies an array size. Within the function, I attempt to declare 
: an array of int's:
: 
: int item_count [array_size];

Dynamically determining the size of an array allocated on the stack is
a gcc extension. If you need a dynamic array, you should use 'vector'
instead of a built-in array. Actually, you should not use built-in
array any where else than in some classes to implement them (this is
not a language requirement but results from the style built-in arrays
are dealt with by the language).

: If it's something in the ANSI standard, I'd appreciate the paragraph 
: reference as well as a simple description of what's going on. Thanks.

dcl.array verse 1: there is explicitly stated that the expression used
to determine the size of an array has to be const. You can also have a
look at a current discussion in comp.std.c++ concerning dynamic array
bounds (for built-in arrays). The thread is titled "Array
Initialization".
--
dietmar.kuehl@uni-konstanz.de
http://www.informatik.uni-konstanz.de/~kuehl
I am a realistic optimist - that's why I appear to be slightly pessimistic