lib/mbsnlen.c

   1 /* Counting the multibyte characters in a string.
   2    Copyright (C) 2007-2025 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2007.
   4
   5    This file is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    This file is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #include <config.h>
  19
  20 /* Specification.  */
  21 #include <string.h>
  22
  23 #include <stdlib.h>
  24
  25 #if GNULIB_MCEL_PREFER
  26 # include "mcel.h"
  27 #else
  28 # include "mbiterf.h"
  29 #endif
  30
  31 /* Return the number of multibyte characters in the character string starting
  32    at STRING and ending at STRING + LEN.  */
  33 size_t
  34 mbsnlen (const char *string, size_t len)
  35 {
  36   if (MB_CUR_MAX > 1)
  37     {
  38       size_t count = 0;
  39
  40       const char *string_end = string + len;
  41
  42 #if GNULIB_MCEL_PREFER
  43       for (; string < string_end; string += mcel_scan (string, string_end).len)
  44         count++;
  45 #else
  46       mbif_state_t state;
  47       const char *iter;
  48       for (mbif_init (state), iter = string; mbif_avail (state, iter, string_end); )
  49         {
  50           mbchar_t cur = mbif_next (state, iter, string_end);
  51           count++;
  52           iter += mb_len (cur);
  53         }
  54 #endif
  55
  56       return count;
  57     }
  58   else
  59     return len;
  60 }