strsep(3) - Man pages

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 de-
       limiter 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 re-
       turns 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) con-
       forms 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,  how-
       ever, 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), str-
       tok(3)

Linux man-pages 6.9.1              2024-06-15                         strsep(3)

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