MirBSD manpage: strtok(3), strtok_r(3)

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


     strtok, strtok_r - string token operations


     #include <string.h>

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

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


     This interface is obsoleted by strsep(3).

     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 separator string, sep, must be supplied each time, and may change
     between calls.

     The strtok_r() function is a version of strtok() that takes an explicit
     context argument and is reentrant.

     The strtok() and strtok_r() functions return a pointer to the beginning
     of each subsequent token in the string, after replacing the separator
     character itself with an ASCII NUL character. When no more tokens remain,
     a null pointer is returned.

     Since strtok() and strtok_r() modify the string, str should not point to
     an area in the initialized data segment.


     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))) {
                   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".


     memchr(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 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 starting
     point, such a sequence of calls would always return NULL.

MirBSD #10-current              June 29, 1991                                1

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