STRTOK(3)

NAME
strtok, strtok_r - string tokens

LIBRARY
libc

SYNOPSIS
#include <string.h>
char *
strtok(char * restrict str, const char * restrict sep);
char *
strtok_r(char * restrict str, const char * restrict sep, char ** restrict last);

DESCRIPTION
This interface is obsoleted by strsep(3).

The strtok() function is used to isolate sequential tokens in a null-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 implementation will behave as if no library function calls strtok().

The strtok_r() function is a reentrant version of strtok(). The context pointer last must be provided on each call. The strtok_r() function may also be used to nest two parsing loops within one another, as long as separate context pointers are used.

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

EXAMPLES
The following uses strtok_r() to parse two strings using separate contexts:

    char test[80], blah[80];
    char *sep = "\\/:;=-";
    char *word, *phrase, *brkt, *brkb;
    strcpy(test, "This;is.a:test:of=the/string\\tokenizer-function.");
    for (word = strtok_r(test, sep, &brkt);
         word;
         word = strtok_r(NULL, sep, &brkt))
    {
        strcpy(blah, "blah:blat:blab:blag");
        for (phrase = strtok_r(blah, sep, &brkb);
             phrase;
             phrase = strtok_r(NULL, sep, &brkb))
        {
            printf("So far we're at %s:%s\n", word, phrase);
        }
    }

SEE ALSO
memchr(3), strchr(3), strcspn(3), strpbrk(3), strrchr(3), strsep(3), strspn(3), strstr(3), wcstok(3)

STANDARDS
The strtok() function conforms to isoC.

AUTHORS
Wes Peters, Softweyr LLC <wes@softweyr.com>

Based on the FreeBSD 3.0 implementation.

BUGS
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) 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.