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       strtok, strtok_r - extract tokens from strings


       #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 ||


       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

       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 arguments.


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


              SVr4, POSIX.1-2001, 4.3BSD, C89, C99.



       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.


       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>

       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",

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

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


       Another example program using strtok() can be found in getaddrinfo_a(3).


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


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