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.\" Hyphenation exceptions
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.\" gd_spf.3.  The gd_spf 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_spf 3 "25 December 2016" "Version 0.10.0" "GETDATA"

.SH NAME
gd_spf \(em returns the samples per frame for a field in a
dirfile

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

.SH DESCRIPTION
The
.FN gd_spf
function queries a dirfile(5) database specified by
.ARG dirfile
and determines the number of samples per frame for the field
.ARG field_code .
This information is also available from
.F3 gd_entry .

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

.SH RETURN VALUE
Upon successful completion,
.FN gd_spf
returns a positive integer indicating the number of samples per frame for the
field specified.  On error, it returns zero and stores a negative-valued error
code in the
.B DIRFILE
object which may be retrieved by a subsequent call to
.F3 gd_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.
.DD GD_E_DIMENSION
A scalar field was found where a vector field was expected.
.DD GD_E_INTERNAL_ERROR
An internal error occurred in the library while trying to perform the task.
This indicates a bug in the library.  Please report the incident to the
maintainer.
.DD GD_E_RECURSE_LEVEL
Too many levels of recursion were encountered while trying to resolve
.ARG field_code .
This usually indicates a circular dependency in field specification in the
dirfile.
.PP
A descriptive error string for the error may be obtained by calling
.F3 gd_error_string .

.SH HISTORY
The
.FN get_spf
function appeared in GetData-0.3.0.

In GetData-0.7.0, this function was renamed to
.FN gd_spf .

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_error ,
.F3 gd_error_string ,
.F3 gd_open ,
dirfile(5)