strsep(3) — Linux manual page

strsep(3)               Library Functions Manual               strsep(3)

NAME

       strsep - extract token from string

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

       None.

HISTORY

       4.4BSD.

       The strsep() function was introduced as a replacement for
       strtok(3), since the latter cannot handle empty fields.  However,
       strtok(3) conforms to C89/C99 and hence is more portable.

BUGS

       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.

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);
       }

SEE ALSO

       memchr(3), strchr(3), string(3), strpbrk(3), strspn(3),
       strstr(3), strtok(3)

COLOPHON

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Linux man-pages 6.9.1          2024-06-15                      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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