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229a60e4d5
Changed calc_errno a global int variable so that is may be directly accessed by libcalc users. Further improve help files for help/errno, help/error, help/newerror, help/stoponerror and help/strerror by adding to documentation of the calc error code system as well as libcalc interface where applicable.
96 lines
3.3 KiB
Plaintext
96 lines
3.3 KiB
Plaintext
NAME
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errno - return or set a stored error-number
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SYNOPSIS
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errno([errnum])
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TYPES
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errnum integer
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return integer
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DESCRIPTION
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Whenever an operation or evaluation of function returns an error-value,
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the numerical code for that value is stored as "global calc_errno value".
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The term "global calc_errno value" is an internal calc state.
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This is NOT a calc variable called calc_errno.
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NOTE:
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The errno() builtin should not be confused with the errno
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used by libc in C. The range of errnum extend beyond the
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C's libc errno. See help error for information on the mean
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of various errnum ranges.
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Unlike error() calling errno() does NOT increment the global
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calc error count (see help errcount).
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errno() returns the current value of "global calc_errno value".
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Unlike error() calling errno() does NOT increment the global
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calc error count (see help errcount).
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errno(errnum) sets "global calc_errno value" to the value errnum
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and returns its previous value. Unlike error(errnum) calling
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errno(errnum) does NOT increment the global calc error count
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(see help errcount).
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To detect whether an error occurs during some sequence of operations,
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one may immediately before that sequence set the stored error-number
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to zero by errno(0), and then after the operations, whether or not
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an error has occurred will be indicated by errno() being nonzero or
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zero. If a non-zero value is returned, that value will be the code
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for the most recent error encountered.
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The default argument for the functions error() and strerror() is the
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currently stored error-number; in particular, if no error-value has
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been returned after the last errno(0), strerror() will return
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"No error".
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EXAMPLE
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; ## Assuming there is no file with name "not_a_file"
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; errcount(0),; errmax(20),;
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; print errcount(), errmax()
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0 20
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; badfile = fopen("not_a_file", "r")
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; print errcount(), errno(), strerror()
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1 2 No such file or directory
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; a = 1/0
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; print errcount(), errno(), strerror()
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2 10001 Division by zero
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LIMITS
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0 <= errnum <= 32767
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LINK LIBRARY
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int calc_errno; /* global calc_errno value */
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SEE ALSO
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errmax, errcount, error, strerror, iserror, newerror, errorcodes,
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stoponerror
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## Copyright (C) 1999-2006,2021,2023 Landon Curt Noll
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##
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## Calc is open software; you can redistribute it and/or modify it under
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## the terms of the version 2.1 of the GNU Lesser General Public License
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## as published by the Free Software Foundation.
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##
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## Calc is distributed in the hope that it will be useful, but WITHOUT
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## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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## or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
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## Public License for more details.
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##
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## A copy of version 2.1 of the GNU Lesser General Public License is
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## distributed with calc under the filename COPYING-LGPL. You should have
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## received a copy with calc; if not, write to Free Software Foundation, Inc.
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## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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##
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## Under source code control: 1994/10/27 03:05:08
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## File existed as early as: 1994
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##
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## chongo <was here> /\oo/\ http://www.isthe.com/chongo/
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## Share and enjoy! :-) http://www.isthe.com/chongo/tech/comp/calc/
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