STRTOK(3) | Linux Programmer's Manual | STRTOK(3) |
NAME
strtok, strtok_r - extract tokens from stringsSYNOPSIS
#include<string.h>
char *strtok(char * str , const char * delim );
char *strtok_r(char * str , const char * delim , char ** saveptr );
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
DESCRIPTION
The strtok() function breaks a string into a sequence of zero or more nonempty tokens. On the first call to strtok() the string to be parsed should be specified in str. In each subsequent call that should parse the same string, str must be NULL.RETURN VALUE
The strtok() and strtok_r() functions return a pointer to the next token, or NULL if there are no more tokens.ATTRIBUTES
Multithreading (see pthreads(7))
The strtok() function is not thread-safe.The strtok_r() function is thread-safe.
CONFORMING TO
- strtok()
- SVr4, POSIX.1-2001, 4.3BSD, C89, C99.
- strtok_r()
- POSIX.1-2001.
BUGS
Be cautious when using these functions. If you do use them, note that:- *
- These functions modify their first argument.
- *
- These functions cannot be used on constant strings.
- *
- The identity of the delimiting byte is lost.
- *
- The strtok() function uses a static buffer while parsing, so it's not thread safe. Use strtok_r() if this matters to you.
EXAMPLE
The program below uses nested loops that employ strtok_r() to break a string into a two-level hierarchy of tokens. The first command-line argument specifies the string to be parsed. The second argument specifies the delimiter byte(s) to be used to separate that string into "major" tokens. The third argument specifies the delimiter byte(s) to be used to separate the "major" tokens into subtokens.An example of the output produced by this program is the following:
$ ./a.out 'a/bbb///cc;xxx:yyy:'':;''/'
1: a/bbb///cc
--> a
--> bbb
--> cc
2: xxx
--> xxx
3: yyy
--> yyy
Program source
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int
main(int argc, char *argv[])
{
char *str1, *str2, *token, *subtoken;
char *saveptr1, *saveptr2;
int j;
if (argc != 4) {
fprintf(stderr, "Usage: %s string delim subdelim\n",
argv[0]);
exit(EXIT_FAILURE);
}
for (j = 1, str1 = argv[1]; ; j++, str1 = NULL) {
token = strtok_r(str1, argv[2], &saveptr1);
if (token == NULL)
break;
printf("%d: %s\n", j, token);
for (str2 = token; ; str2 = NULL) {
subtoken = strtok_r(str2, argv[3], &saveptr2);
if (subtoken == NULL)
break;
printf("--> %s\n", subtoken);
}
}
exit(EXIT_SUCCESS);
}
Another example program using strtok() can be found in getaddrinfo_a(3).
SEE ALSO
index(3), memchr(3), rindex(3), strchr(3), string(3), strpbrk(3), strsep(3), strspn(3), strstr(3), wcstok(3)COLOPHON
This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.2013-05-19 | GNU |