r6:Function:slist get head and then next
Source Files
/src/slist/slist_get_and_set.c /inc/liblfds.h
Prototype
struct slist_element *slist_get_head_and_next( struct slist_state *ss, struct slist_element **se );
Parameters
struct slist_state *ss
- An slist state as allocated by slist_new.
struct slist_element **se
- A pointer to a pointer which will be set to point to an slist element. When this function is first called, *se must be NULL (e.g. the value of the pointer pointed to by this argument must be NULL).
Return Value
When *se is NULL, *se is set to point to the head element and the new value of *se is returned.
When *se is not NULL, *se is set to point to the element immediately after *se and the new value of *se is returned. This value will be NULL if there was no element after the original value of *se.
Notes
This function is for use in loops. When we first come into the loop, we have set *se to NULL, so the function sets *se to the head element. When we loop, because *se is not NULL, the function there-after sets *se to the next element in the list.
Without this function, the slist_get_head function must be used before the loop, with the slist_get_next function being then used inside the loop, like so;
struct slist_element
*se;
slist_get_head( ss, &se );
while( se != NULL )
{
...
slist_get_next( se, &se );
}
With it, the loop is rewritten thus;
strut slist_element
*se = NULL;
while( slist_get_head_and_then_next(ss, &se) )
{
...
}