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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!
149 lines
4.7 KiB
Plaintext
149 lines
4.7 KiB
Plaintext
NAME
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search - search for an element satisfying a specified condition
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SYNOPSIS
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search(a, b [, [c] [, [d] ] ])
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TYPES
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a matrix, list, association or file
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b string if a is a file, otherwise any
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c integer, defaults to zero or current file-position
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d integer, defaults to size(a) or current file-position
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return nonnegative integer or null value
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DESCRIPTION
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Negative values of c and nonpositive values for d are treated as
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offsets from size(a), i.e. as if c were replaced by size(a) + c,
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and d by size(a) + d. Any such adjustment is assumed in the following
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description.
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For Non-file a:
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For a matrix, list, or association a,
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search(a, b, c, d) returns, if it exists, the least index i for which
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c <= i < d, 0 <= i < size(a), and, if accept() has not been defined,
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a[[i]] == b, or if accept() has been defined, accept(a[[i]], b)
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tests as nonzero. The null value is returned if there is no such i.
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For example, to search for the first a[[i]] > b an appropriate
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accept() function is given by:
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define accept(v,b) = (v > b);
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To restore the original behavior of search(), one may then use
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define accept(v, b) = (v == b).
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Since the addresses (rather than values) of a and b are passed,
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the values of v = x[[i]] and b may be changed during execution
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of search(a, b, c, d), e.g. if accept(v,b) has been defined by
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define accept(v,b) = (v > b ? v-- : b++);
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For a is a file-stream:
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c defaults to the current file-position if there are just two
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arguments (a,b) or if there are four arguments as in (a,b, ,d)
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where d is an integer. Otherwise c defaults to zero.
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d defaults to the current file-position or size(a) according as
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the number of arguments (indicated by commas) is four or less
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than four.
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If a is a file, a string formed by n successive characters in a
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is considered to occur at the file position
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of the first character. E.g. if a has the characters "123456",
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the string "345" is said to occur at position 2.
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The file is searched forwards from file-position pos = c for
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a match with b (not including the terminating '\0').
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Only characters with file-positions less than d are considered,
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so the effective interval for the first-character position pos
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for a matching string is limited by both c <= pos <= d - strlen(b)
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and 0 <= pos < size(a) - strlen(b).
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The function returns pos if a match is found, and the reading position
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for the stream after the search will then correspond to the position of
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the terminating '\0' for the string b.
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The null value is returned if no match is found. If c, d, size(a)
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and strlen(b) are such that no match is possible, no reading of the
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file occurs and the current file-position is not changed. In a case
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where characters are read, the final file-position will be
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min(d, size(a)) - strlen(b) + 1,
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i.e. the file will be at the first position where a match is impossible
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because the specified search region has insufficient remaining characters.
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EXAMPLE
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; L = list(2,"three",4i)
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; search(L,"three")
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1
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; search(L,"threes")
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; search(L, 4i, 4)
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; search(L, 4i, 1)
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2
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; f = fopen("foo", "w+")
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; fputs(f, "This file has 28 characters.")
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; rewind(f)
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; search(f, "ha")
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10
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; ftell(f)
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12
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; search(f, "ha")
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18
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; search(f, "ha")
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; search(f, "ha",)
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10
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; search(f, "ha", 12)
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18
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; search(f, "ha", -10)
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18
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; search(f, "ha", ,)
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10
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; search(f, "ha", 11, 19)
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; ftell(f)
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18
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; search(f, "ha", 11, 20)
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18
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; search(f, "ha", 5, 500)
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10
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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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append, delete, insert, islist, pop, push, remove, rsearch,
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select, size,
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assoc, list, mat
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## Copyright (C) 1999-2006 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: 1994/03/19 03:13:21
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## File existed as early as: 1994
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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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