.\" header.tmac. GetData manual macros. .\" .\" Copyright (C) 2016 D. V. Wiebe .\" .\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" .\" .\" 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. .\" Format a function name with optional trailer: func_name()trailer .de FN \" func_name [trailer] .nh .BR \\$1 ()\\$2 .hy .. .\" Format a reference to section 3 of the manual: name(3)trailer .de F3 \" func_name [trailer] .nh .BR \\$1 (3)\\$2 .hy .. .\" Format the header of a list of definitons .de DD \" name alt... .ie "\\$2"" \{ \ .TP 8 .PD .B \\$1 \} .el \{ \ .PP .B \\$1 .PD 0 .DD \\$2 \\$3 \} .. .\" Start a code block: Note: groff defines an undocumented .SC for .\" Bell Labs man legacy reasons. .de SC .fam C .na .nh .. .\" End a code block .de EC .hy .ad .fam .. .\" Format a structure pointer member: struct->member\fRtrailer .de SPM \" struct member trailer .nh .ie "\\$3"" .IB \\$1 ->\: \\$2 .el .IB \\$1 ->\: \\$2\fR\\$3 .hy .. .\" Format a function argument .de ARG \" name trailer .nh .ie "\\$2"" .I \\$1 .el .IR \\$1 \\$2 .hy .. .\" Hyphenation exceptions .hw sarray carray lincom linterp .\" gd_constants.3. The gd_constants man page. .\" .\" Copyright (C) 2008, 2010, 2011, 2015, 2016 D.V. Wiebe .\" .\"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" .\" .\" 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_constants 3 "25 December 2016" "Version 0.10.0" "GETDATA" .SH NAME gd_constants, gd_mconstants \(em retrieve a list of constant values from a Dirfile .SH SYNOPSIS .SC .B #include .HP .BI "const void *gd_constants(DIRFILE *" dirfile ", gd_type_t .IB return_type ); .HP .BI "const void *gd_mconstants(DIRFILE *" dirfile ", const char" .BI * parent ", gd_type_t " return_type ); .EC .SH DESCRIPTION The .FN gd_constants function queries a dirfile(5) database specified by .ARG dirfile and compiles a list of values of the all .B CONST fields defined in the database, excluding meta subfields. The values returned are converted to the data type specified by .ARG return_type . The .ARG return_type should be one of the following symbols: .IP .SC .BR GD_UINT8 ,\~ GD_INT8 ,\~ GD_UINT16 ,\~ GD_INT16 ,\~ GD_UINT32 ,\~ GD_INT32 , .BR GD_UINT64, \~ GD_INT64 ,\~ GD_FLOAT32 ,\~ GD_FLOAT64 ,\~ GD_COMPLEX64 , .BR GD_COMPLEX128 . .EC .PP See .F3 gd_get_constant for the meaning of these symbols. The .ARG dirfile argument must point to a valid DIRFILE object previously created by a call to .F3 gd_open . The .FN gd_mconstants function returns the same list for .B CONST meta subfields of the parent field specified by .ARG parent . A corresponding list of names for these fields may be obtained by calling .F3 gd_field_list_by_type or .F3 gd_mfield_list_by_type . .SH RETURN VALUE Upon successful completion, .FN gd_constants returns a pointer to an array containing the values of all the constants defined in the dirfile database. Similarly, .FN gd_mconstants returns a pointer to an array containing the values of the all the meta subfield constants of the specified parent field. 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 CONST fields returned by .F3 gd_field_list_by_type or .F3 gd_mfield_list_by_type . The array is unterminated. The number of values in the array can be obtained from a call to .F3 gd_nfields_by_type or .F3 gd_nmfields_by_type , as appropriate. Memory for the returned array is managed by GetData and should not be de-allocated by the caller. The caller may not modify any values in the array. Doing so may cause database corruption. The pointer returned is guaranteed to be valid only until the function is called again, with the exception that, since each top-level field maintains its own arrays, calling .FN gd_mconstants for a one parent field does not invalidate the pointer returned for a any other parent. Modifying the dirfile's metadata invalidates any pointer returned by these functions. And no pointers remain valid after the dirfile is de-allocated by a call to .F3 gd_close or .F3 gd_discard . Once a pointer is invalidated, the caller should not dereference it. If no constants of the appropriate class are defined in the database, NULL is returned. This is not considered an error. On error, these functions return NULL and store 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_ALLOC The library was unable to allocate memory. .DD GD_E_BAD_CODE The specified .ARG parent field code was not found, or referred to a metafield .RB ( gd_mconstants () only). .DD GD_E_BAD_DIRFILE The supplied dirfile was invalid. .DD GD_E_BAD_TYPE The .ARG return_type specified was not one of the symbols listed above. .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 GetData developers. .PP A descriptive error string for the error may be obtained by calling .F3 gd_error_string . .SH HISTORY The functions .FN get_constants and .FN get_mconstants appeared in GetData-0.4.0. In GetData-0.7.0, these functions were renamed to .FN gd_constants and .FN gd_mconstants . .SH SEE ALSO .F3 gd_error , .F3 gd_error_string , .F3 gd_field_list_by_type , .F3 gd_get_constant , .F3 gd_mfield_list_by_type , .F3 gd_nfields_by_type , .F3 gd_nmfields_by_type , .F3 gd_open , dirfile(5)