gd_nfields3
Count field entries in a dirfile
Part of gd_nentries(3).
Usage
#include <getdata.h>
unsigned int gd_nentries(DIRFILE *dirfile, const char *parent, unsigned int type, unsigned int flags);
unsigned int gd_nfields(DIRFILE *dirfile);
unsigned int gd_nfields_by_type(DIRFILE *dirfile, gd_entype_t type);
unsigned int gd_nmfields(DIRFILE *dirfile, const char *parent);
unsigned int gd_nmfields_by_type(DIRFILE *dirfile, const char *parent, gd_entype_t type);
unsigned int gd_nmvectors(DIRFILE *dirfile, const char *parent);
unsigned int gd_nvectors(DIRFILE *dirfile);
Overview
The gd_nentries() function queries a dirfile(5) database specified by dirfile and counts the number of metadata entries satisfying the provided criteria. If parent is non-NULL, metafields under the field specified by parent are considered; otherwise, top-level fields are considered, and metafields ignored.
The type argument should be one of the following symbols indicating an explicit entry type to count:
-
GD_BIT_ENTRY,GD_CARRAY_ENTRY,GD_CONST_ENTRY,GD_DIVIDE_ENTRY,GD_INDEX_ENTRY,GD_INDIR_ENTRY,GD_LINCOM_ENTRY,GD_LINTERP_ENTRY,GD_MPLEX_ENTRY,GD_MULTIPLY_ENTRY,GD_PHASE_ENTRY,GD_POLYNOM_ENTRY,GD_RAW_ENTRY,GD_RECIP_ENTRY,GD_SARRAY_ENTRY,GD_SBIT_ENTRY,GD_SINDIR_ENTRY,GD_STRING_ENTRY,GD_WINDOW_ENTRY.
(GD_INDEX_ENTRY is a special field type for the implicit INDEX field) or else one of the following special symbols:
.TP 8 GD_ALL_ENTRIES (=0) Count entries of all types.
.TP 8 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 8 GD_SCALAR_ENTRIES Count only scalar field types (CONST, CARRAY, SARRAY, STRING).
.TP 8 GD_VECTOR_ENTRIES Count only numeric-valued vector field types (all field types except SINDIR and the scalar field types listed above).
The flags argument should be zero or more of the following flags, bitwise or'd together:
.TP 8 GD_ENTRIES_HIDDEN Include hidden entries (see gd_hidden(3)) in the count: normally hidden entries are skipped;
.TP 8 GD_ENTRIES_NOALIAS Exclude aliases from the count: normally aliases are considered the same as their target (that is: a field with n aliases, plus its canonical name, will be counted n+1 times).
This function has a subset of the functionality of the gd_match_entries(3) function (q.v.).
Special Cases
The call
gd_nfields(dirfile);
is equivalent to
gd_nentries(dirfile, NULL, GD_ALL_ENTRIES, 0);
The call
gd_nfields_by_type(dirfile, type);
is equivalent to
gd_nentries(dirfile, NULL, type, 0);
The call
gd_nmfields(dirfile, parent);
is equivalent to
gd_nentries(dirfile, parent, GD_ALL_ENTRIES, 0);
The call
gd_nmfields_by_type(dirfile, parent, type);
is equivalent to
gd_nentries(dirfile, parent, type, 0);
The call
gd_nmvectors(dirfile, parent);
is equivalent to
gd_nentries(dirfile, parent, GD_VECTOR_ENTRIES, 0);
The call
gd_nvectors(dirfile);
is equivalent to
gd_nentries(dirfile, NULL, GD_VECTOR_ENTRIES, 0);
Return value
Upon successful completion, these functions return an unsigned in indicating the number of entries in the database satisfying the supplied criteria.
On error, these functions return zero and store a negative-valued error code in the DIRFILE object which may be retrieved by a subsequent call to gd_error(3). Possible error codes are:
.TP 8 GD_E_BAD_CODE The supplied parent field code was not found, or referred to a metafield itself.
.TP 8 GD_E_BAD_DIRFILE The supplied dirfile was invalid.
.TP 8 GD_E_BAD_ENTRY The type parameter supplied was not one of the symbols listed above.
A descriptive error string for the error may be obtained by calling gd_error_string(3).
Releases
7 releases since Debian 7 (Wheezy); the text changed 2 times.