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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ATTRIBUTES | STANDARDS | HISTORY | CAVEATS | EXAMPLES | SEE ALSO | COLOPHON |
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strsep(3) Library Functions Manual strsep(3)
strsep - extract token from string
Standard C library (libc, -lc)
#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
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.
The strsep() function returns a pointer to the token, that is, it
returns the original value of *stringp.
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├──────────────────────────────────────┼───────────────┼─────────┤
│ strsep() │ Thread safety │ MT-Safe │
└──────────────────────────────────────┴───────────────┴─────────┘
BSD.
4.4BSD.
The strsep() function was introduced as a replacement for
strtok(3), since the latter cannot handle empty fields.
Be cautious when using this function. If you do use it, note
that:
• This function modifies its first argument.
• This function cannot be used on constant strings.
• The identity of the delimiting character is lost.
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);
}
memchr(3), strchr(3), string(3), strpbrk(3), strspn(3), strstr(3),
strtok(3)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
[email protected]
Linux man-pages 6.15 2025-05-17 strsep(3)
Pages that refer to this page: memchr(3), strchr(3), string(3), strpbrk(3), strspn(3), strstr(3), strtok(3)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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