.\" gd_mstrings.3.  The gd_mstrings man page.
.\"
.\" Copyright (C) 2008, 2010, 2011 D. V. Wiebe
.\"
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.\" This file is part of the GetData project.
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.\" any later version published by the Free Software Foundation; with no
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.TH gd_mstrings 3 "19 October 2011" "Version 0.8.0" "GETDATA"
.SH NAME
gd_mstrings \(em retrieve a list of string values from a dirfile
.SH SYNOPSIS
.B #include <getdata.h>
.HP
.nh
.ad l
.BI "const char **gd_mstrings(DIRFILE *" dirfile ", const char *" parent );
.hy
.ad n
.SH DESCRIPTION
The
.BR gd_mstrings ()
function queries a dirfile(5) database specified by
.I dirfile
and returns a read-only list of values of the all
.B STRING
type metafields for the supplied
.I parent
field.

The 
.I dirfile
argument must point to a valid DIRFILE object previously created by a call to
.BR gd_open (3).

The array returned will be de-allocated by a call to
.BR gd_close (3)
and should not be de-allocated by the caller.  The list returned should not be
assumed to be in any particular order, although it is guaranteed to be in the
same order as the list of
.B STRING
fields returned by
.BR gd_mfield_list_by_type (3).
The array is terminated by a NULL pointer.  The number of strings in the array
can be obtained from a call to
.BR gd_nmfields_by_type (3).

The caller may not modify any strings in the array, or the array itself.  Doing
so may cause database corruption.  The pointer returned is guaranteed to be
valid until
.BR gd_mstrings ()
is called again with the same arguments, or until the array is de-allocated by
a call to
.BR gd_close (3).

A corresponding list of names for these fields may be obtained by calling
.BR gd_mfield_list_by_type (3).

.SH RETURN VALUE
Upon successful completion,
.BR gd_mstrings ()
returns a pointer to an array of strings containing the values of all the
.B STRING
metafields for the specified parent field.  The array is terminated by a NULL
pointer.  If no strings are defined in the database for the specified parent, an
array consisting of only the NULL pointer is returned.  On error it returns NULL
and sets the dirfile error to a non-zero error value.  Possible error values
are:
.TP 8
.B GD_E_ALLOC
The library was unable to allocate memory.
.TP
.B GD_E_BAD_CODE
The supplied parent field code was not found, or referred to a metafield itself.
.TP
.B GD_E_BAD_DIRFILE
The supplied dirfile was invalid.
.PP
The dirfile error may be retrieved by calling
.BR gd_error (3).
A descriptive error string for the last error encountered can be obtained from
a call to
.BR gd_error_string (3).
.SH SEE ALSO
.BR dirfile (5),
.BR gd_open (3),
.BR gd_error (3),
.BR gd_error_string (3),
.BR gd_mfield_list_by_type (3),
.BR gd_nmfields_by_type (3),
.BR gd_strings (3)