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81 lines
2.3 KiB
Plaintext
81 lines
2.3 KiB
Plaintext
NAME
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. - oldvalue
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SYNOPSIS
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. (with no adjacent letters or digits or _ or .)
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TYPES
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return any
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DESCRIPTION
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The "old value" is essentially a global variable with identifier "."
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which at top level when directly from a file or keyboard
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is automatically assigned the saved value for a line
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of statements when evaluation of that line is completed and this saved
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value is not null. A line of statements is normally completed by a
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'\n' not within a block bounded by braces or an expression bounded by
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parentheses.
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Disabling of saving by calling saveval(0) causes lines to return a
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null value and . then becomes in effect a global variable whose
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value may be changed by assignments and operations like ++ and --.
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A null value may be assigned to . by . = null() or free(.).
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EXAMPLE
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> saveval(1);
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> a = 2
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> .
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2
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> . += 3; b = . + 4
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> print ., b
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9 9
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> . += 3; b = . + 4; null()
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> print ., b
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12 16
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> list(a, b, a + b)
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list (3 elements, 3 nonzero):
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[[0]] = 2
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[[1]] = 16
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[[2]] = 18
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> saveval(0)
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> print pop(.), .[[1]]
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2 18
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LIMITS
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none
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LINK LIBRARY
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none
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SEE ALSO
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saveval
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## Copyright (C) 1999 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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## 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
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##
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## @(#) $Revision: 29.1 $
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## @(#) $Id: oldvalue,v 29.1 1999/12/14 09:16:01 chongo Exp $
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## @(#) $Source: /usr/local/src/cmd/calc/help/RCS/oldvalue,v $
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##
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## Under source code control: 1997/09/06 20:03:35
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## File existed as early as: 1997
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##
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## chongo <was here> /\oo/\ http://reality.sgi.com/chongo/
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## Share and enjoy! :-) http://reality.sgi.com/chongo/tech/comp/calc/
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