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scripts/strings/substr.m

changeset 10289: 4b124317dc38
parent:eb63fbe60fab
author: John W. Eaton <jwe@octave.org>
date: Tue Feb 09 20:58:55 2010 -0500 (61 minutes ago)
permissions: -rw-r--r--
description: base_properties::set_children: account for hidden children 
     1## Copyright (C) 1996, 1999, 2000, 2004, 2005, 2006, 2007, 2008,

     2##               2009 Kurt Hornik

     3##

     4## This file is part of Octave.

     5##

     6## Octave is free software; you can redistribute it and/or modify it

     7## under the terms of the GNU General Public License as published by

     8## the Free Software Foundation; either version 3 of the License, or (at

     9## your option) any later version.

    10##

    11## Octave is distributed in the hope that it will be useful, but

    12## WITHOUT ANY WARRANTY; without even the implied warranty of

    13## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    14## General Public License for more details.

    15##

    16## You should have received a copy of the GNU General Public License

    17## along with Octave; see the file COPYING.  If not, see

    18## <http://www.gnu.org/licenses/>.

    19

    20## -*- texinfo -*-

    21## @deftypefn {Function File} {} substr (@var{s}, @var{offset}, @var{len})

    22## Return the substring of @var{s} which starts at character number

    23## @var{offset} and is @var{len} characters long.

    24##

    25## If @var{offset} is negative, extraction starts that far from the end of

    26## the string.  If @var{len} is omitted, the substring extends to the end

    27## of S.

    28##

    29## For example,

    30##

    31## @example

    32## @group

    33## substr ("This is a test string", 6, 9)

    34##      @result{} "is a test"

    35## @end group

    36## @end example

    37##

    38## This function is patterned after AWK.  You can get the same result by

    39## @code{@var{s}(@var{offset} : (@var{offset} + @var{len} - 1))}.

    40## @end deftypefn

    41

    42## Author: Kurt Hornik <Kurt.Hornik@wu-wien.ac.at>

    43## Adapted-By: jwe

    44

    45function t = substr (s, offset, len)

    46

    47  if (nargin < 2 || nargin > 3)

    48    print_usage ();

    49  endif

    50

    51  if (ischar (s))

    52    nc = columns (s);

    53    if (abs (offset) > 0 && abs (offset) <= nc)

    54      if (offset <= 0)

    55        offset += nc + 1;

    56      endif

    57      if (nargin == 2)

    58        eos = nc;

    59      else

    60        eos = offset + len - 1;

    61      endif

    62      if (eos <= nc)

    63        t = s (:, offset:eos);

    64      else

    65        error ("substr: length = %d out of range", len);

    66      endif

    67    else

    68      error ("substr: offset = %d out of range", offset);

    69    endif

    70  else

    71    error ("substr: expecting string argument");

    72  endif

    73

    74endfunction

    75

    76%!assert(strcmp (substr ("This is a test string", 6, 9), "is a test"));

    77

    78%!error substr ();

    79

    80%!error substr ("foo", 2, 3, 4);

    81