NAME
    strerror - returns a string describing an error value

SYNOPSIS
    strerror([errnum | "E_STRING"])

TYPES
    errnum	integer
    E_STRING	string

    return	string

DESCRIPTION
    With errno(errnum) numeric argument:

	strerror(errnum) will return one of:

	* system error and libc errno value related string
	* calc computation error code string
	* user-defined description string created by newerror(str)
	* "Unknown error errnum" (where errnum is in decimal)

    With strerror("E_STRING") string argument:

	If E_STRING is a valid errsym code, then the E_STRING errsym
	is converted into strerror(errnum).

	If E_STRING is not a valid errsym code, an error error condition
	is raised about the invalid E_STRING.

	For example, these two calls are equivalent:

	    cstrerror(10003);	/* error 10003 has a E_STRING of "E_ADD" */
	    cstrerror("E_ADD");	/* error 10003 has a E_STRING of "E_ADD" */

	See help errstr for information on E_STRING errsym codes.

	For a list of the E_STRING associated with calc computation error
	codes, see help errorcodes.

    Without a argument, strerror() returns as if it were called with:

	strerror(errno())

    That is, the string associated with the "global calc_errno value"
    is returned.

    The term "global calc_errno value" is an internal calc state.
    This is NOT a calc variable called calc_errno.

    The system error and libc errno value related string may be
    different for different systems.

    For users of libcalc:

	The libcalc array error_table[] contains the hard coded
	calc-generated error array of ECOUNT+2 pointers to strings
	starting with E__BASE, ending with E__HIGHEST and terminated
	by a NULL pointer.

	The error_table[0] is for errnum of E__BASE, and is the
	string "No error".

	The error_table[ECOUNT] is string associated with the
	highest calc-generated error message.

	The error_table[ECOUNT+1] is a NULL pointer.

     See help error for more information on the ranges of errnum and
     the meaning of the above mentioned constants.

EXAMPLE
    ; errcount(0),; errmax(20),;
    ; print errcount(), errmax()
    0 20

    ; print strerror(2)
    No such file or directory
    ; print errcount(), errmax()
    0 20

    ; x = 3 / 0;
    ; print errcount(), errmax()
    1 20
    ; print strerror()
    Division by zero

    ; a = newerror("alpha")
    ; print errcount(), errmax()
    2 20
    ; print strerror()
    alpha

    ; print strerror(999)
    Unknown error: 999
    ; print errcount(), errmax()
    2 20

LIMITS
    0 <= errnum <= 32767

    E_STRING is string that must match the regular expression: ^E_[A-Z0-9_]+$

LINK LIBRARY
    int calc_errno;				/* global calc_errno value */

    CONST struct errtbl error_table[ECOUNT+2];	/* calc error codes, error symbols and error messages */

SEE ALSO
    errcount, errmax, errno, errorcodes, errstr, iserror, newerror, stoponerror

    strcat, strcpy, strlen, strncmp, strncpy, strpos,
    strprintf, strscan, strscanf, substr,

## Copyright (C) 1999-2006,2023  Landon Curt Noll
##
## Calc is open software; you can redistribute it and/or modify it under
## the terms of the version 2.1 of the GNU Lesser General Public License
## as published by the Free Software Foundation.
##
## Calc is distributed in the hope that it will be useful, but WITHOUT
## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
## or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU Lesser General
## Public License for more details.
##
## A copy of version 2.1 of the GNU Lesser General Public License is
## distributed with calc under the filename COPYING-LGPL.  You should have
## received a copy with calc; if not, write to Free Software Foundation, Inc.
## 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
##
## Under source code control:	1996/04/30 03:05:18
## File existed as early as:	1996
##
## chongo <was here> /\oo/\	http://www.isthe.com/chongo/
## Share and enjoy!  :-)	http://www.isthe.com/chongo/tech/comp/calc/