3 ms·

First off, strtok() is dead, long live strsep(). Secondly, this is C code--it's pretty low-level. Yes, strsep() messes with your input. But that is very well d

First off, strtok() is dead, long live strsep(). Secondly, this is C code--it's pretty low-level. Yes, strsep() messes with your input. But that is very well documented. If you don't want it to, strdup() beforehand (or strndup() if you don't trust the input). His whole example of strtok() dying on a character constant is stupid--why on earth would you do that? If you've got a string constant you may as well just have the constant array and save yourself the parsing headache. This isn't rocket science.

scdlbx 16y ago
Always use strndup(). Never trust your input.
- apenwarr 16y ago
  If you're trying to strdup() something you're not even sure is null-terminated, you're already doomed.
  - scott_s 16y ago
    The parent said to use strndup(), which takes a max value of characters to copy.
    - CamperBob 16y ago
      And adds a \0 after the characters copied, which means you have to remember to do the sizeof(dest)-1 thing to avoid an overwrite. The people who designed the C string functions should have been made to pee in a cup before they were allowed into the building. So much trouble could have been avoided if they had only been consistent about using memory block sizes as parameters rather than "string" (sic) lengths.
      - scott_s 16y ago
        Which is annoying, yes, but using strndup() negates apenwarr's point.
      - __david__ 16y ago
        What are you talking about? There is no sizeof(dest) with strndup()--it's newly allocated memory sized appropriately so there's no chance of an overwrite.
        tptacek 16y ago
        While we're on the subject, what is the point of strndup()? Keeping people from running you out of memory with big long strings? They'll just find other ways to do the same thing (by repeatedly feeding you strings of threshold length).
        CamperBob 16y ago
        (Actually it was strncpy's wacky behavior I was thinking of. I don't think I've ever used strndup().)
dfox 16y ago
I tend to use and recommend str(c)spn, which althought more low-level are more flexible and often what you want. And also you don't have to modify input if you don't want to.
- tptacek 16y ago
  strcspn is really, really fussy. When what you want is the semantic equivalent of "foo,bar, baz".split(','), I don't think it's worth the potential for error, or the tangliness of the code.

scdlbx 16y ago

Always use strndup(). Never trust your input.

apenwarr 16y ago
If you're trying to strdup() something you're not even sure is null-terminated, you're already doomed.
- scott_s 16y ago
  The parent said to use strndup(), which takes a max value of characters to copy.
  - CamperBob 16y ago
    And adds a \0 after the characters copied, which means you have to remember to do the sizeof(dest)-1 thing to avoid an overwrite. The people who designed the C string functions should have been made to pee in a cup before they were allowed into the building. So much trouble could have been avoided if they had only been consistent about using memory block sizes as parameters rather than "string" (sic) lengths.
    - scott_s 16y ago
      Which is annoying, yes, but using strndup() negates apenwarr's point.
    - __david__ 16y ago
      What are you talking about? There is no sizeof(dest) with strndup()--it's newly allocated memory sized appropriately so there's no chance of an overwrite.
      - tptacek 16y ago
        While we're on the subject, what is the point of strndup()? Keeping people from running you out of memory with big long strings? They'll just find other ways to do the same thing (by repeatedly feeding you strings of threshold length).
      - CamperBob 16y ago
        (Actually it was strncpy's wacky behavior I was thinking of. I don't think I've ever used strndup().)

dfox 16y ago

I tend to use and recommend str(c)spn, which althought more low-level are more flexible and often what you want. And also you don't have to modify input if you don't want to.

tptacek 16y ago
strcspn is really, really fussy. When what you want is the semantic equivalent of "foo,bar, baz".split(','), I don't think it's worth the potential for error, or the tangliness of the code.