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1 ## Copyright (C) 1996 Kurt Hornik |
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2 ## |
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3 ## This file is part of Octave. |
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4 ## |
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5 ## Octave is free software; you can redistribute it and/or modify it |
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6 ## under the terms of the GNU General Public License as published by |
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7 ## the Free Software Foundation; either version 2, or (at your option) |
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8 ## any later version. |
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9 ## |
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10 ## Octave is distributed in the hope that it will be useful, but |
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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13 ## General Public License for more details. |
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14 ## |
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15 ## You should have received a copy of the GNU General Public License |
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16 ## along with Octave; see the file COPYING. If not, write to the Free |
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17 ## Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
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18 ## 02110-1301, USA. |
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19 |
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20 ## -*- texinfo -*- |
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21 ## @deftypefn {Function File} {} substr (@var{s}, @var{beg}, @var{len}) |
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22 ## Return the substring of @var{s} which starts at character number |
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23 ## @var{beg} and is @var{len} characters long. |
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24 ## |
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25 ## If OFFSET is negative, extraction starts that far from the end of |
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26 ## the string. If LEN is omitted, the substring extends to the end |
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27 ## of S. |
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28 ## |
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29 ## For example, |
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30 ## |
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31 ## @example |
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32 ## substr ("This is a test string", 6, 9) |
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33 ## @result{} "is a test" |
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34 ## @end example |
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35 ## |
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36 ## @quotation |
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37 ## This function is patterned after AWK. You can get the same result by |
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38 ## @code{@var{s} (@var{beg} : (@var{beg} + @var{len} - 1))}. |
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39 ## @end quotation |
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40 ## @end deftypefn |
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41 |
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42 ## Author: Kurt Hornik <Kurt.Hornik@wu-wien.ac.at> |
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43 ## Adapted-By: jwe |
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44 |
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45 function t = substr (s, offset, len) |
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46 |
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47 if (nargin < 2 || nargin > 3) |
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48 usage ("substr (s, offset, len)"); |
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49 endif |
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50 |
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51 if (ischar (s)) |
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52 nc = columns (s); |
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53 if (abs (offset) > 0 && abs (offset) <= nc) |
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54 if (offset > 0) |
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55 beg = offset; |
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56 else |
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57 beg = nc + offset + 1; |
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58 endif |
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59 if (nargin == 2) |
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60 eos = nc; |
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61 else |
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62 eos = beg + len - 1; |
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63 endif |
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64 if (eos <= nc) |
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65 t = s (:, beg:eos); |
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66 else |
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67 error ("substr: length = %d out of range", len); |
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68 endif |
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69 else |
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70 error ("substr: offset = %d out of range", offset); |
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71 endif |
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72 else |
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73 error ("substr: expecting string argument"); |
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74 endif |
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75 |
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76 endfunction |
