Files
calc/help/oldvalue
Landon Curt Noll a31078bbec Remove all RCS @(#) lines and RCS strings
Some folks might think: “you still use RCS”?!?  And we will say,
hey, at least we switched from SCCS to RCS back in … I think it was
around 1994 ... at least we are keeping up! :-) :-) :-)

Logs say that SCCS version 18 became RCS version 19 on 1994 March 18.

RCS served us well.  But now it is time to move on.   And so we are
switching to git.

Calc releases produce a lot of file changes.  In the 125 releases
of calc since 1996, when I started managing calc releases, there
have been 15473 file mods!
2017-05-23 01:33:23 -07:00

77 lines
2.2 KiB
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NAME
. - oldvalue
SYNOPSIS
. (with no adjacent letters or digits or _ or .)
TYPES
return any
DESCRIPTION
The "old value" is essentially a global variable with identifier "."
which at top level when directly from a file or keyboard
is automatically assigned the saved value for a line
of statements when evaluation of that line is completed and this saved
value is not null. A line of statements is normally completed by a
'\n' not within a block bounded by braces or an expression bounded by
parentheses.
Disabling of saving by calling saveval(0) causes lines to return a
null value and . then becomes in effect a global variable whose
value may be changed by assignments and operations like ++ and --.
A null value may be assigned to . by . = null() or free(.).
EXAMPLE
; saveval(1);
; a = 2
; .
2
; . += 3; b = . + 4
; print ., b
9 9
; . += 3; b = . + 4; null()
; print ., b
12 16
; list(a, b, a + b)
list (3 elements, 3 nonzero):
[[0]] = 2
[[1]] = 16
[[2]] = 18
; saveval(0)
; print pop(.), .[[1]]
2 18
LIMITS
none
LINK LIBRARY
none
SEE ALSO
saveval
## Copyright (C) 1999 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: 1997/09/06 20:03:35
## File existed as early as: 1997
##
## chongo <was here> /\oo/\ http://www.isthe.com/chongo/
## Share and enjoy! :-) http://www.isthe.com/chongo/tech/comp/calc/