test

来自「Calc Software Package for Number Calc」· 代码 · 共 83 行

NAME
    test - whether a value is deemed to be true or false

SYNOPSIS
    test(x)

TYPES
    x		any

    return	0 or 1

DESCRIPTION
    This function returns 1 or 0 according as x tests as "true" or "false".

    Conditions under which a value x is considered to be false are:

	Numbers (real or complex):  x is zero

	String: x == ""

	Matrix: every component of x tests as false

	List: every element of x tests as false

	Association: x has no element

	File: x is not open

	Null: always

	Object of type xx: if xx_test has been defined, xx_test(x)
		returns zero;  if xx_test has not been defined,
		every element of x tests as false.

	Error-value or other types: never

EXAMPLE
    ; print test(27), test(0), test("abc"), test("")
    1 0 1 0

    ; print test(mat[3] = {1,,2}), test(mat[2][2])
    1 0

    ; A = list(0, 2, 0)
    ; print test(A), test(pop(A)), test(A), test(pop(A)), test(A)
    1 0 1 1 0

LIMITS
    none

LINK LIBRARY
    none

SEE ALSO
    isassoc, isfile, isident, isnum, isint, islist, ismat, isnull, isobj,
    isreal, isstr, issimple, istype

## Copyright (C) 1999-2006  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.
## 59 Temple Place, Suite 330, Boston, MA  02111-1307, USA.
##
## @(#) $Revision: 29.3 $
## @(#) $Id: test,v 29.3 2006/06/10 12:28:10 chongo Exp $
## @(#) $Source: /usr/local/src/cmd/calc/help/RCS/test,v $
##
## Under source code control:	1996/07/11 01:05:13
## 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/