strtok, strtok_r - string tokens
Standard C Library (libc, -lc)
strtok(char * restrict str, const char * restrict sep);
strtok_r(char *str, const char *sep, char **lasts);
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
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 delineate tokenizing to a single string at a time when using
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 C''). The
strtok_r() function conforms to IEEE Std 1003.1c-1995 (``POSIX.1'').
There is no way to get tokens from multiple strings simultaneously.
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.
BSD February 3, 1994 BSD
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