On: 18 Oct 03  23:54:32 Bo Simonsen wrote to Roger Scudder:

 > So you set it to NULL after freeing it?

 >  RS> #include "sniptype.h"  /* for macro FREE(x) */

 This is a simple mechanism that can be employed as part of a robust memory
allocation scheme.  The C standard specifies that if free() is passed a
pointer with a value of NULL the pointer is to be  ignored.  (So like to
test in their code, but AFAIK that is not necessary When a program contains
a large number of pointers and dynamic allocation is used frequently it is
very important to know at all times exactly where those pointers are
pointing.  The idea is to always set pointers equal to NULL when they are
defined and after the block they point to has been free'd.

 > #define FREE(x) free(x); x = NULL;
 > or?

 Yes, that will work as well.  One thing though...  when writing a macro,
always surround the operands with parens.

#define FREE(x)    free(x); (x)=NULL;

I find the version in snippets more elligant (I had originally written one
like yours) because it works as one statement instead of two.  It is a
minor difference, so don't sweat it if you want to use your version.

-Roger

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