.\" mtk, 2010-09-09: Noted glibc 2.4 bug, added info on circular
.\" lists, added example program
.\"
-.TH INSQUE 3 2016-03-15 "" "Linux Programmer's Manual"
+.TH INSQUE 3 2019-03-06 "" "Linux Programmer's Manual"
.SH NAME
insque, remque \- insert/remove an item from a queue
.SH SYNOPSIS
.nf
.B #include <search.h>
-.sp
+.PP
.BI "void insque(void *" elem ", void *" prev );
-
+.PP
.BI "void remque(void *" elem );
.fi
-.sp
+.PP
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
-.sp
+.PP
.ad l
.BR insque (),
.BR remque ():
The linked list may be linear (i.e., NULL forward pointer at
the end of the list and NULL backward pointer at the start of the list)
or circular.
-
+.PP
The
.BR insque ()
function inserts the element pointed to by \fIelem\fP
immediately after the element pointed to by \fIprev\fP.
-
+.PP
If the list is linear, then the call
.I "insque(elem, NULL)"
can be used to insert the initial list element,
and the call sets the forward and backward pointers of
.I elem
to NULL.
-
+.PP
If the list is circular,
the caller should ensure that the forward and backward pointers of the
first element are initialized to point to that element,
argument of the
.BR insque ()
call should also point to the element.
-
+.PP
The
.BR remque ()
function removes the element pointed to by \fIelem\fP from the
.BR remque ()
T} Thread safety MT-Safe
.TE
-
+.sp 1
.SH CONFORMING TO
POSIX.1-2001, POSIX.1-2008.
.SH NOTES
.\" e.g., SunOS, Linux libc4 and libc5
the arguments of these functions were of type \fIstruct qelem *\fP,
defined as:
-
+.PP
.in +4n
-.nf
+.EX
struct qelem {
struct qelem *q_forw;
struct qelem *q_back;
char q_data[1];
};
-.fi
+.EE
.in
-
+.PP
This is still what you will get if
.B _GNU_SOURCE
is defined before
including \fI<search.h>\fP.
-
+.PP
The location of the prototypes for these functions differs among several
versions of UNIX.
The above is the POSIX version.
The program below demonstrates the use of
.BR insque ().
Here is an example run of the program:
+.PP
.in +4n
-.nf
-
+.EX
.RB "$ " "./a.out -c a b c"
Traversing completed list:
a
b
c
That was a circular list
-.fi
+.EE
.in
.SS Program source
\&
-.nf
+.EX
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
e = malloc(sizeof(struct element));
if (e == NULL) {
- fprintf(stderr, "malloc() failed\\n");
+ fprintf(stderr, "malloc() failed\en");
exit(EXIT_FAILURE);
}
}
if (errfnd || optind >= argc) {
- fprintf(stderr, "Usage: %s [\-c] string...\\n", argv[0]);
+ fprintf(stderr, "Usage: %s [\-c] string...\en", argv[0]);
exit(EXIT_FAILURE);
}
/* Traverse the list from the start, printing element names */
- printf("Traversing completed list:\\n");
+ printf("Traversing completed list:\en");
elem = first;
do {
- printf(" %s\\n", elem\->name);
+ printf(" %s\en", elem\->name);
elem = elem\->forward;
} while (elem != NULL && elem != first);
if (elem == first)
- printf("That was a circular list\\n");
+ printf("That was a circular list\en");
exit(EXIT_SUCCESS);
}
-.fi
+.EE
+.SH SEE ALSO
+.BR queue (3)