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

       4.4BSD.

NOTES

       The strsep() function was introduced as a replacement  for  strtok(3),  since  the  latter
       cannot  handle  empty  fields.   However,  strtok(3)  conforms  to  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)