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19819340ff
Added help/errorcodes rule to the top level Makefile. Added E_USERMAX symbol (== 32767) to indicate the maximum value allowed for user error codes. Improve help/error. Added text about error code ranges and range symbols.
128 lines
3.5 KiB
Plaintext
128 lines
3.5 KiB
Plaintext
NAME
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error - generate a value of specified error type
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SYNOPSIS
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error([n])
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TYPES
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n integer, defaults to errno()
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return null value or error value
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DESCRIPTION
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If n == 0:
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error(n) returns the null value.
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The "global calc_errno value" is set to 0.
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The global calc error count is not changed.
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For 0 < n <= 32767:
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error(n) returns a value that is of a special type called
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"error". The "error" return value, when given to iserror()
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will cause that function to return a true value that happens
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to match the "global calc_errno value".
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The "global calc_errno value" is then set to n.
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The global calc error count (see help errcount) is incremented.
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If the global calc error count exceeds the maximum count
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(see help errmax), any ongoing calc execution is aborted.
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All other values of n are reserved for future use and currently
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will generate an error.
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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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The "global calc_errno value" be set to some other non-zero
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value by other builtin functions and calculations, especially
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if they result in an error. Thus, while calling errno(n) may
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set calc_errno, some other error may later overwrite the
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"global calc_errno value".
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By convention, the "global calc_errno value" has the following ranges:
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n < 0 Reserved for future use
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n == 0 calc_errno cleared: libc errno codes above here
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1 <= n <= 9999 system error and libc errno codes
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n == 10000 Reserved for "No error" calc internal state
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10001 <= n <= E__HIGHEST calc computation error codes
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E__HIGHEST < n < 20000 Reserved for future calc error codes
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20000 < n <= 32767 User defined error codes start here
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n >= 32768 Reserved for future use
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The following constants are part of the calc error code mechanism:
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E__BASE == 10000
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E_USERDEF == 20000
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E_USERMAX == 32767
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E__BASE < E__HIGHEST < E_USERDEF
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E__COUNT == E__HIGHEST - E__BASE
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See help errorcodes for the actual values of the above constants.
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EXAMPLE
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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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; a = error(10009)
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; print errcount(), errmax()
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1 20
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; print a
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Error 10009
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; print iserror(a)
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10009
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; strerror(a)
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"Bad argument for inverse"
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; b = error(0)
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; print errcount(), errmax()
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1 20
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; print isnull(b)
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1
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LIMITS
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0 <= n <= 32767
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LINK LIBRARY
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none
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SEE ALSO
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errcount, errmax, errorcodes, iserror, errno, strerror, newerror,
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stoponerror
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## Copyright (C) 1999-2006,2023 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: 1995/12/18 03:30:59
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## File existed as early as: 1995
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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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