.\" gd_nentries.3.  The gd_nentries man page.
.\"
.\" Copyright (C) 2012 D. V. Wiebe
.\"
.\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
.\"
.\" This file is part of the GetData project.
.\"
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.\" under the terms of the GNU Free Documentation License, Version 1.2 or
.\" any later version published by the Free Software Foundation; with no
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.TH gd_nentries 3 "28 June 2012" "Version 0.8.0" "GETDATA"
.SH NAME
gd_nentries, gd_nfields, gd_nfields_by_type gd_nmfields, gd_nmfields_by_type,
gd_nmvectors, gd_nvectors \(em count field entries in a dirfile
.SH SYNOPSIS
.B #include <getdata.h>
.HP
.nh
.ad l
.BI "unsigned int gd_nentries(DIRFILE *" dirfile ", const char *" parent ,
.BI "unsigned int " type ", unsigned int " flags );
.HP
.BI "unsigned int gd_nfields(DIRFILE *" dirfile );
.HP
.BI "unsigned int gd_nfields_by_type(DIRFILE *" dirfile ", gd_entype_t " type );
.HP
.BI "unsigned int gd_nmfields(DIRFILE *" dirfile ", const char *" parent );
.HP
.BI "unsigned int gd_nmfields_by_type(DIRFILE *" dirfile ,
.BI "const char *" parent ", gd_entype_t " type );
.HP
.BI "unsigned int gd_nmvectors(DIRFILE *" dirfile ", const char *" parent );
.HP
.BI "unsigned int gd_nvectors(DIRFILE *" dirfile );
.hy
.ad n
.SH DESCRIPTION
The
.BR gd_nentries ()
function queries a dirfile(5) database specified by
.I dirfile
and returns a count of metadata entries satisfying the supplied criteria.
If
.I parent
is non-NULL, metafields under the field specified by
.I parent
are considered; otherwise, top-level fields are considered, and metafields
ignored.

The
.I type
argument should be one of the following symbols indicating an explicit entry
type to count:
.IP
.nh
.ad l
.BR GD_BIT_ENTRY ", " GD_CARRAY_ENTRY ", " GD_CONST_ENTRY ", " GD_DIVIDE_ENTRY ,
.BR GD_INDEX_ENTRY ", " GD_LINCOM_ENTRY ", " GD_LINTERP_ENTRY ,
.BR GD_MPLEX_ENTRY ", " GD_MULTIPLY_ENTRY ", " GD_PHASE_ENTRY ,
.BR GD_POLYNOM_ENTRY ", " GD_RAW_ENTRY ", " GD_RECIP_ENTRY ,
.BR GD_SBIT_ENTRY ", " GD_STRING_ENTRY ", " GD_WINDOW_ENTRY .
.ad n
.hy
.PP
.RB ( GD_INDEX_ENTRY
is a special field type for the implicit
.I INDEX
field) or else one of the following special symbols:
.TP
.B GD_ALL_ENTRIES \fR(= 0)
Count entries of all types.
.TP
.B GD_ALIAS_ENTRIES
Count only aliases.  This is the only way to get a count including aliases which
do not point to valid field codes.
.TP
.B GD_SCALAR_ENTRIES
Count only scalar field types
.RB ( CONST ", " CARRAY ", " STRING ).
.TP
.B GD_VECTOR_ENTRIES
Count only vector field types (all field types except the scalar field types
listed above).
.PP
The
.I flags
argument should be zero or more of the following flags, bitwise or'd together:
.TP
.B GD_ENTRIES_HIDDEN
Include hidden entries (see
.BR gd_hidden (3))
in the count: normally hidden entries are skipped;
.TP
.B GD_ENTRIES_NOALIAS
Exclude aliases from the count: normally aliases are considered the same as
their target (that is: a field with
.I n
aliases, plus its canonical name, will be counted
.IR n +1
times).
.SS Special Cases
The call
.RS
.BI gd_nfields( dirfile );
.RE
.PP
is equivalent to
.RS
.BI gd_nentries( dirfile ", NULL, GD_ALL_ENTRIES, 0);
.RE
.PP
The call
.RS
.BI gd_nfields_by_type( dirfile ", " type );
.RE
.PP
is equivalent to
.RS
.BI gd_nentries( dirfile ", NULL, " type ", 0);"
.RE
.PP
The call
.RS
.BI gd_nmfields( dirfile ", " parent );
.RE
.PP
is equivalent to
.RS
.BI gd_nentries( dirfile ", " parent ", GD_ALL_ENTRIES, 0);"
.RE
.PP
The call
.RS
.BI gd_nmfields_by_type( dirfile ", " parent ", " type );
.RE
.PP
is equivalent to
.RS
.BI gd_nentries( dirfile ", " parent ", " type ", 0);"
.RE
.PP
The call
.RS
.BI gd_nmvectors( dirfile ", " parent );
.RE
.PP
is equivalent to
.RS
.BI gd_nentries( dirfile ", " parent ", GD_VECTOR_ENTRIES, 0);"
.RE
.PP
The call
.RS
.BI gd_nvectors( dirfile );
.RE
.PP
is equivalent to
.RS
.BI gd_nentries( dirfile ", NULL, GD_VECTOR_ENTRIES, 0);"
.RE

.SH RETURN VALUE
Upon successful completion, these functions return the number of entries in the
database satisfying the supplied criteria.  On error, they return 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.
.TP
.B GD_E_BAD_ENTRY
The
.I type
parameter supplied was not one of the symbols listed above.
.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_entry_list (3),
.BR gd_error (3),
.BR gd_error_string (3),
.BR gd_hidden (3)