home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Cream of the Crop 1
/
Cream of the Crop 1.iso
/
PROGRAM
/
CBASE102.ARJ
/
BTFIRST.C
< prev
next >
Wrap
Text File
|
1991-09-23
|
2KB
|
98 lines
/* Copyright (c) 1989 Citadel */
/* All Rights Reserved */
/* #ident "@(#)btfirst.c 1.5 - 91/09/23" */
#include <ansi.h>
/* ansi headers */
#include <errno.h>
/* library headers */
#include <blkio.h>
/* local headers */
#include "btree_.h"
/*man---------------------------------------------------------------------------
NAME
btfirst - first btree key
SYNOPSIS
#include <btree.h>
int btfirst(btp)
btree_t *btp;
DESCRIPTION
The btfirst function positions the cursor of btree btp on the
first key in that btree.
btfirst will fail if one or more of the following is true.
[EINVAL] btp is not a valid btree pointer.
[BTELOCK] btp is not locked.
[BTENKEY] btp is empty.
[BTENOPEN] btp is not open.
SEE ALSO
btkeycnt, btlast, btnext, btprev.
DIAGNOSTICS
Upon successful completion, a value of 0 is returned. Otherwise,
a value of -1 is returned, and errno set to indicate the error.
------------------------------------------------------------------------------*/
#ifdef AC_PROTO
int btfirst(btree_t *btp)
#else
int btfirst(btp)
btree_t *btp;
#endif
{
int terrno = 0; /* tmp errno */
/* validate arguments */
if (!bt_valid(btp)) {
errno = EINVAL;
return -1;
}
/* check if not open */
if (!(btp->flags & BTOPEN)) {
errno = BTENOPEN;
return -1;
}
/* check locks */
if (!(btp->flags & BTLOCKS)) {
errno = BTELOCK;
return -1;
}
/* set cursor to first key */
btp->cbtpos.node = btp->bthdr.first;
btp->cbtpos.key = 1;
/* check if tree is empty */
if (btp->cbtpos.node == NIL) {
btp->cbtpos.key = 0;
bt_ndinit(btp, btp->cbtnp);
errno = BTENKEY;
return -1;
}
/* read current node */
if (bt_ndget(btp, btp->cbtpos.node, btp->cbtnp) == -1) {
BTEPRINT;
terrno = errno;
btp->cbtpos.node = NIL;
btp->cbtpos.key = 0;
bt_ndinit(btp, btp->cbtnp);
errno = terrno;
return -1;
}
return 0;
}