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NetBSD 6.1.5 - man page for strtok (netbsd section 3)

STRTOK(3)			   BSD Library Functions Manual 			STRTOK(3)

     strtok, strtok_r -- string tokens

     Standard C Library (libc, -lc)

     #include <string.h>

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

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

     The strtok() function is used to isolate sequential tokens in a nul-terminated 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 further tokens from the same string, should pass a null pointer instead.  The separa-
     tor string, sep, must be supplied each time, and may change between calls.

     The strtok() function returns a pointer to the beginning of each subsequent 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

     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 necessary to limit tokenizing to a single string at a time when using strtok_r().

     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".

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

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

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

BSD					 August 11, 2002				      BSD

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