INSQUE

insque, remque ? insert/remove an item from a queue

#include <stdlib.h>

void insque(struct qelem *elem, struct qelem *prev);
void remque(struct qelem *elem);

insque() and remque() are functions for manipulating queues made from doubly-linked lists. Each element in this list is of type struct qelem

The qelem structure is defined as

struct qelem {
    struct    qelem *q_forw;
    struct    qelem *q_back;
    char      q_data[1];
};

insque() inserts the element pointed to by elem immediately after the element pointed to by prev, which must NOT be NULL.

remque() removes the element pointed to by elem from the doubly-linked list.

SVR4

The q_data field is sometimes defined to be type char *, and under solaris 2.x, it doesn’t appear to exist at all.

The location of the prototypes for these functions differ among several versions of UNIX. Some systems place them in <search.h>, others in <string.h>. Linux places them in <stdlib.h> since that seems to make the most sense.

Some versions of UNIX (like HP-UX 10.x) do not define a struct qelem but rather have the arguments to insque() and remque() be of type void *.