STRTOK(3)                                           Linux Programmer's Manual                                          STRTOK(3)



NAME
       strtok, strtok_r - extract tokens from strings

SYNOPSIS
       #include <string.h>

       char *strtok(char *str, const char *delim);

       char *strtok_r(char *str, const char *delim, char **saveptr);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       strtok_r(): _SVID_SOURCE || _BSD_SOURCE || _POSIX_C_SOURCE >= 1 || _XOPEN_SOURCE || _POSIX_SOURCE

DESCRIPTION
       The  strtok()  function parses a string into a sequence of tokens.  On the first call to strtok() the string to be parsed
       should be specified in str.  In each subsequent call that should parse the same string, str should be NULL.

       The delim argument specifies a set of characters that delimit the tokens in the parsed string.  The  caller  may  specify
       different strings in delim in successive calls that parse the same string.

       Each  call  to  strtok()  returns  a pointer to a null-terminated string containing the next token.  This string does not
       include the delimiting character.  If no more tokens are found, strtok() returns NULL.

       A sequence of two or more contiguous delimiter characters in the parsed string is considered to be  a  single  delimiter.
       Delimiter characters at the start or end of the string are ignored.  Put another way: the tokens returned by strtok() are
       always nonempty strings.

       The strtok_r() function is a reentrant version strtok().  The saveptr argument is a pointer to a char * variable that  is
       used internally by strtok_r() in order to maintain context between successive calls that parse the same string.

       On  the  first  call to strtok_r(), str should point to the string to be parsed, and the value of saveptr is ignored.  In
       subsequent calls, str should be NULL, and saveptr should be unchanged since the previous call.

       Different strings may be parsed concurrently using sequences of calls to strtok_r() that specify different saveptr  argu-
       ments.

RETURN VALUE
       The strtok() and strtok_r() functions return a pointer to the next token, or NULL if there are no more tokens.

CONFORMING TO
       strtok()
              SVr4, POSIX.1-2001, 4.3BSD, C89, C99.

       strtok_r()
              POSIX.1-2001.

BUGS
       Be cautious when using these functions.  If you do use them, note that:

       * These functions modify their first argument.

       * These functions cannot be used on constant strings.

       * The identity of the delimiting character is lost.

       * The  strtok()  function uses a static buffer while parsing, so it's not thread safe.  Use strtok_r() if this matters to
         you.

EXAMPLE
       The program below uses nested loops that employ strtok_r() to break a string into a two-level hierarchy of  tokens.   The
       first  command-line argument specifies the string to be parsed.  The second argument specifies the delimiter character(s)
       to be used to separate that string into "major" tokens.  The third argument specifies the delimiter  character(s)  to  be
       used to separate the "major" tokens into subtokens.

       An example of the output produced by this program is the following:

           $ ./a.out 'a/bbb///cc;xxx:yyy:' ':;' '/'
           1: a/bbb///cc
                    --> a
                    --> bbb
                    --> cc
           2: xxx
                    --> xxx
           3: yyy
                    --> yyy

   Program source

       #include <stdio.h>
       #include <stdlib.h>
       #include <string.h>

       int
       main(int argc, char *argv[])
       {
           char *str1, *str2, *token, *subtoken;
           char *saveptr1, *saveptr2;
           int j;

           if (argc != 4) {
               fprintf(stderr, "Usage: %s string delim subdelim\n",
                       argv[0]);
               exit(EXIT_FAILURE);
           }

           for (j = 1, str1 = argv[1]; ; j++, str1 = NULL) {
               token = strtok_r(str1, argv[2], &saveptr1);
               if (token == NULL)
                   break;
               printf("%d: %s\n", j, token);

               for (str2 = token; ; str2 = NULL) {
                   subtoken = strtok_r(str2, argv[3], &saveptr2);
                   if (subtoken == NULL)
                       break;
                   printf(" --> %s\n", subtoken);
               }
           }

           exit(EXIT_SUCCESS);
       } /* main */

SEE ALSO
       index(3), memchr(3), rindex(3), strchr(3), strpbrk(3), strsep(3), strspn(3), strstr(3), wcstok(3)

COLOPHON
       This  page  is  part of release 3.25 of the Linux man-pages project.  A description of the project, and information about
       reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



GNU                                                        2008-10-29                                                  STRTOK(3)