string/strtok.c

   1 /* Copyright (C) 1991,1996,1997,1999,2000,2001,2007
   2    Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library 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 GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <string.h>
  20
  21
  22 static char *olds;
  23
  24 #undef strtok
  25
  26 /* Parse S into tokens separated by characters in DELIM.
  27    If S is NULL, the last string strtok() was called with is
  28    used.  For example:
  29         char s[] = "-abc-=-def";
  30         x = strtok(s, "-");             // x = "abc"
  31         x = strtok(NULL, "-=");         // x = "def"
  32         x = strtok(NULL, "=");          // x = NULL
  33                 // s = "abc\0=-def\0"
  34 */
  35 char *
  36 strtok (s, delim)
  37      char *s;
  38      const char *delim;
  39 {
  40   char *token;
  41
  42   if (s == NULL)
  43     s = olds;
  44
  45   /* Scan leading delimiters.  */
  46   s += strspn (s, delim);
  47   if (*s == '\0')
  48     {
  49       olds = s;
  50       return NULL;
  51     }
  52
  53   /* Find the end of the token.  */
  54   token = s;
  55   s = strpbrk (token, delim);
  56   if (s == NULL)
  57     /* This token finishes the string.  */
  58     olds = __rawmemchr (token, '\0');
  59   else
  60     {
  61       /* Terminate the token and make OLDS point past it.  */
  62       *s = '\0';
  63       olds = s + 1;
  64     }
  65   return token;
  66 }