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.\" gd_alias_target.3.  The gd_alias_target man page.
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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_alias_target 3 "25 December 2016" "Version 0.10.0" "GETDATA"

.SH NAME
gd_alias_target \(em determine the target of an alias defined in a Dirfile
database

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

.SH DESCRIPTION
The
.FN gd_alias_target
function queries a dirfile(5) database specified by
.ARG dirfile
and determines the target field code of the alias specified by
.ARG alias_name .

The
.ARG dirfile
argument must point to a valid DIRFILE object previously created by a call to
.F3 gd_open .

Note: the target may itself be the an alias, which will have its own target.  To
obtain the canonical name of the field ultimately referenced by
.ARG alias_name ,
pass it to
.F3 gd_entry
and inspect the
.ARG field
member of the gd_entry_t structure returned.

.SH RETURN VALUE
Upon successful completion,
.FN gd_alias_target
returns a pointer to a read-only character string containing the name of the
target of the specified alias.  On error,
.FN gd_alias_target
returns NULL and sets the dirfile error a non-zero error value.  Possible error
values are:
.DD GD_E_BAD_CODE
The name
.ARG alias_name
was not found in the dirfile.
.B GD_E_BAD_DIRFILE
The supplied dirfile was invalid.
.DD GD_E_BAD_FIELD_TYPE
The entry specified by
.ARG alias_name
was not an alias.
.PP
The dirfile error may be retrieved by calling
.F3 gd_error .
A descriptive error string for the last error encountered can be obtained from
a call to
.F3 gd_error_string .

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

.SH SEE ALSO
.F3 gd_aliases ,
.F3 gd_entry ,
.F3 gd_open ,
dirfile(5)