STRTOK(3) | 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 *restrict str,
const char *restrict sep, char
**restrict 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
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.
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); } }
memchr(3), strchr(3), strcspn(3), strpbrk(3), strrchr(3), strsep(3), strspn(3), strstr(3), wcstok(3)
The strtok
() function conforms to
ISO/IEC 9899:1990
(“ISO C90”).
Wes Peters, Softweyr LLC: ⟨wes@softweyr.com⟩
Based on the FreeBSD 3.0 implementation.
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
.
November 27, 1998 | macOS 14.6 |