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.\" gd_hidden.3.  The gd_hidden man page.
.\"
.\" Copyright (C) 2012, 2013, 2015, 2016 D. V. Wiebe
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.\" This file is part of the GetData project.
.\"
.\" Permission is granted to copy, distribute and/or modify this document
.\" under the terms of the GNU Free Documentation License, Version 1.2 or
.\" any later version published by the Free Software Foundation; with no
.\" Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
.\" Texts.  A copy of the license is included in the `COPYING.DOC' file
.\" as part of this distribution.
.\"
.TH gd_hidden 3 "25 December 2016" "Version 0.10.0" "GETDATA"

.SH NAME
gd_hidden \(em check whether a Dirfile entry is hidden or not

.SH SYNOPSIS
.SC
.B #include <getdata.h>
.HP
.BI "int gd_hidden(const DIRFILE *" dirfile ", const char"
.BI * entry_name );
.EC

.SH DESCRIPTION
The
.FN gd_hidden
function queries a dirfile(5) database specified by
.ARG dirfile
to determine whether the field or alias called
.ARG entry_name
is hidden or not.  This information is also available in the entry object
proved by
.F3 gd_entry .

By default, a hidden entry does not appear in the lists returned by the
functions
.F3 gd_match_entries ,
.F3 gd_entry_list
.F3 gd_constants ,
or
.F3 gd_strings ,
including the special-case versions of
.F3 gd_entry_list
such as
.F3 gd_field_list .
These omissions are also reflected in the counts returned by the corresponding
field counting function
.F3 gd_nentries
and it's special-case versions
.RB ( gd_nfields (3),
&c.).

.SH RETURN VALUE
Upon successful completion,
.FN gd_hidden
returns one if the field or alias is hidden, or zero if the entry is not hidden.

On error, it returns a negative-valued error code.  (As a result, the caller
checking simply whether the return value of this function is non-zero is usually
an error.)  Possible error codes are:
.DD GD_E_BAD_CODE
The field specified by
.ARG field_code
was not found in the database.
.DD GD_E_BAD_DIRFILE
The supplied dirfile was invalid.
.PP
The error code is also stored in the
.B DIRFILE
object and may be retrieved after this function returns by calling
.F3 gd_error .
A descriptive error string for the error may be obtained by calling
.F3 gd_error_string .

.SH HISTORY
The
.FN gd_hidden
function appeared in GetData-0.8.0.

In GetData-0.10.0, the error return from this function changed from -1 to a
negative-valued error code.

.SH SEE ALSO
.F3 gd_entry ,
.F3 gd_field_list ,
.F3 gd_hide ,
.F3 gd_nfields ,
.F3 gd_open ,
.F3 gd_unhide ,
dirfile(5)