.\" gd_nmvectors.3.  The gd_nmvectors man page.
.\"
.\" Copyright (C) 2008, 2010 D. V. Wiebe
.\"
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.\" This file is part of the GetData project.
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.TH gd_nmvectors 3 "16 July 2010" "Version 0.7.0" "GETDATA"
.SH NAME
gd_nmvectors \(em report the number of vector fields in a dirfile
.SH SYNOPSIS
.B #include <getdata.h>
.HP
.nh
.ad l
.BI "unsigned int gd_nmvectors(DIRFILE *" dirfile );
.hy
.ad n
.SH DESCRIPTION
The
.BR gd_nmvectors ()
function queries a dirfile(5) database specified by
.I dirfile
and returns the number of vector metafields defined in the database
.RI ( i.e.
fields of types
.BR BIT ", " LINCOM ", " LINTERP ", " MULTIPLY ", " PHASE ", and " RAW ) for
the supplied parent field.

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

.SH RETURN VALUE
Upon successful completion,
.BR gd_nmvectors ()
returns the number of vector metafields in the dirfile for the given parent.  On
error, it returns zero and sets the dirfile error to a non-zero error value.
Possible error values are:
.TP 8
.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_mvector_list (3),
.BR gd_nmfields (3),
.BR gd_nvectors (3)