INSQUE(3)

NAME
insque, remque - insert/remove an item from a queue

SYNOPSIS
#include <search.h>

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

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

insque(), remque(): _SVID_SOURCE || _XOPEN_SOURCE >= 500

DESCRIPTION
insque() and remque() are functions for manipulating doubly-linked lists. Each element in the list is a structure of which the first two structure elements are a forward and a backward pointer. 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.

CONFORMING TO
POSIX.1-2001

NOTES
Traditionally (e.g., SunOS, Linux libc 4,5) the parameters of these functions were of type struct qelem *, where the struct is defined as
    struct qelem {
        struct qelem *q_forw;
        struct qelem *q_back;
        char          q_data[1];
    };
This is still what you will get if _GNU_SOURCE is defined before including <search.h>. The location of the prototypes for these functions differs among several versions of UNIX. The above is the POSIX version. Some systems place them in <string.h>. Linux libc4,5 placed them in <stdlib.h>.