NAME
strsep - string separate
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#include <string.h>
char *strsep(char **restrict stringp, const char *restrict delim);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
strsep():
Since glibc 2.19:
_DEFAULT_SOURCE
glibc 2.19 and earlier:
_BSD_SOURCE
DESCRIPTION
If *stringp is NULL, the strsep() function returns NULL and does nothing else. Otherwise, this function finds the first token in the string *stringp that is delimited by one of the bytes in the string delim. This token is terminated by overwriting the delimiter with a null byte ('\0'), and *stringp is updated to point past the token. In case no delimiter was found, the token is taken to be the entire string *stringp, and *stringp is made NULL.
RETURN VALUE
The strsep() function returns a pointer to the token, that is, it returns the original value of *stringp.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value |
| strsep() | Thread safety | MT-Safe |
STANDARDS
BSD.
HISTORY
4.4BSD.
The strsep() function was introduced as a replacement for strtok(3), since the latter cannot handle empty fields.
CAVEATS
Be cautious when using this function. If you do use it, note that:
- •
-
The identity of the delimiting character is lost.
EXAMPLES
The program below is a port of the one found in strtok(3), which, however, doesn't discard multiple delimiters or empty tokens:
$ ./a.out 'a/bbb///cc;xxx:yyy:' ':;' '/'
1: a/bbb///cc
--> a
--> bbb
-->
-->
--> cc
2: xxx
--> xxx
3: yyy
--> yyy
4:
-->
Program source
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int
main(int argc, char *argv[])
{
char *token, *subtoken;
if (argc != 4) {
fprintf(stderr, "Usage: %s string delim subdelim\n", argv[0]);
exit(EXIT_FAILURE);
}
for (unsigned int j = 1; (token = strsep(&argv[1], argv[2])); j++) {
printf("%u: %s\n", j, token);
while ((subtoken = strsep(&token, argv[3])))
printf("\t --> %s\n", subtoken);
}
exit(EXIT_SUCCESS);
}