[ILUG] C puzzle
philip.reynolds at rfc-networks.ie
Tue Jul 6 11:40:45 IST 2004
Paul Jakma <paul at clubi.ie> 67 lines of wisdom included:
> list list;
> listmember this;
> listmember next;
> for (this = list->head;
> ((this != NULL) ? next = this->next : next = this);
> this = next)
> Which is not (strictly) allowed.
> Essentially, I have a body of code that uses a macro defined as:
> #define LIST_LOOP(L,V,N) \
> for ((N) = (L)->head; (N); (N) = (N)->next)
> if (((V) = (N)->data) != NULL)
You need to use a temporary variable, to allow the use of free() or
removal of an element in the list.
#define LIST_LOOP(L, V, N, temp) \
for ((N) = (L)->head; \
(N) && ((temp) = (N)->next); \
(N) = (temp))
Something like the above.
Philip Reynolds | RFC Networks Ltd.
philip.reynolds at rfc-networks.ie | +353 (0)1 8832063
http://people.rfc-networks.ie/~phil/ | www.rfc-networks.ie
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