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 noth- ing 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 re- turns the original value of *stringp. ATTRIBUTES For an explanation of the terms used in this section, see at- tributes(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) con- forms 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, 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 6.03 2023-02-05 strsep(3)
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