| STRTOK(3) | Library Functions Manual | STRTOK(3) | 
strtok, strtok_r —
#include <string.h>
char *
  
  strtok(char
    * restrict str, const
    char * restrict sep);
char *
  
  strtok_r(char
    *str, const char
    *sep, char
    **lasts);
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 separator 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 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 necessary to limit
    tokenizing to a single string at a time when using
    strtok_r().
#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”.
strtok() function conforms to ANSI
  X3.159-1989 (“ANSI C89”). The
  strtok_r() function conforms to IEEE
  Std 1003.1c-1995 (“POSIX.1c”).
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) delimiter
  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.
| August 11, 2002 | NetBSD 9.3 |