🚀 go-pugleaf

In article <KANZE.96Apr18105949@gabi.gabi-soft.fr>, kanze@gabi-soft.fr (J. Kanze) writes:
|> In article <4l33ok$oo2@Sherlock.lectra.fr> phil@rd.lectra.fr (Philippe
|> Maurisset) writes:
[...]
|> 
|> |> myexample()
|> |> {
|> |> 	char foo[MAX_X][MAX_Y];
|> |> 	...
|> |> 	myfunc( (char **)foo );
|> |> }
|> 
|> |> void myfunc( char *foo[MAX_X] )
|>                 ^^^^^^^^^^^^^^^^
|> 
|> Because it appears as a function parameter, this is actually a
|> declaration of a char**, and not a char*[].

True.

|> So in fact, you have no type incompatibility to deal with.

Not true.  The original definition of foo in myexample() was as a two-
dimensional array, which, in C, is implemented in storage as a
unidimensional array of size MAX_X*MAX_Y*sizeof(char), not as an array
of pointers-to-characters.  If you try to access this as a pointer-to-a-
pointer, you will be attempting to dereference character data as a
pointer.  (If you've got a real operating system, then this just results
in a core fault.  If you're running on a toy, the results could be far
worse.)

(Of course, the type of the formal argument is compatible with the
cast given in the call, but the cast itself is bogus.)

-- 
James Carlson <carlson@xylogics.com>            Tel:  +1 617 272 8140
Annex Interface Development / Xylogics, Inc.          +1 800 225 3317
53 Third Avenue / Burlington MA  01803-4491     Fax:  +1 617 272 2618