strtok(3) - NetBSD Manual Pages

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STRTOK(3)               NetBSD Library Functions Manual              STRTOK(3)


NAME

     strtok, strtok_r -- string tokens


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <string.h>

     char *
     strtok(char * restrict str, const char * restrict sep);

     char *
     strtok_r(char *str, const char *sep, char **lasts);


DESCRIPTION

     The strtok() function is used to isolate sequential tokens in a nul-ter-
     minated string, str.  These tokens are separated in the string by at
     least one of the characters in sep.  The first time that strtok() is
     called, str should be specified; subsequent calls, wishing to obtain fur-
     ther tokens from the same string, should pass a null pointer instead.
     The separator string, sep, must be supplied each time, and may change
     between calls.

     The strtok() function returns a pointer to the beginning of each subse-
     quent token in the string, after replacing the separator character itself
     with a NUL character.  Separator characters at the beginning of the
     string or at the continuation point are skipped so that zero length
     tokens are not returned.  When no more tokens remain, a null pointer is
     returned.

     The strtok_r() function implements the functionality of strtok() but is
     passed an additional argument, lasts, which points to a user-provided
     pointer which is used by strtok_r() to store state which needs to be kept
     between calls to scan the same string; unlike strtok(), it is not neces-
     sary to limit tokenizing to a single string at a time when using
     strtok_r().


EXAMPLES

     The following will construct an array of pointers to each individual word
     in the string s:

           #define MAXTOKENS       128

           char s[512], *p, *tokens[MAXTOKENS];
           char *last;
           int i = 0;

           snprintf(s, sizeof(s), "cat dog horse cow");

           for ((p = strtok_r(s, " ", &last)); p;
               (p = strtok_r(NULL, " ", &last)), i++) {
                   if (i < MAXTOKENS - 1)
                           tokens[i] = p;
           }
           tokens[i] = NULL;

     That is, tokens[0] will point to "cat", tokens[1] will point to "dog",
     tokens[2] will point to "horse", and tokens[3] will point to "cow".


SEE ALSO

     index(3), memchr(3), rindex(3), strchr(3), strcspn(3), strpbrk(3),
     strrchr(3), strsep(3), strspn(3), strstr(3)


STANDARDS

     The strtok() function conforms to ANSI X3.159-1989 (``ANSI C89'').  The
     strtok_r() function conforms to IEEE Std 1003.1c-1995 (``POSIX.1'').


BUGS

     The System V strtok(), if handed a string containing only delimiter char-
     acters, will not alter the next starting point, so that a call to
     strtok() with a different (or empty) delimiter string may return a
     non-NULL value.  Since this implementation always alters the next start-
     ing point, such a sequence of calls would always return NULL.

NetBSD 10.1                     August 11, 2002                    NetBSD 10.1