4 ms·

A string in C is, by definition, null terminated.

• mlyle 6y ago
  Then why are we providing a length? Plenty of string-handling functions in the c standard library result in no terminating null if max length -- e.g. strncpy. Note the second function is off by one in the opposite direction-- it doesn't find "ok" in "ok".
  • shric 6y ago
    Because the writer of the function doesn't want to bother to check the null terminator. I'm not saying it's a good function, it just doesn't have an issue as long as the input is a valid string with a correct length. strncpy, despite what its name implies, does indeed not necessarily produce strings. Regardless, a C string is defined to have a null terminator. All bets are off if you don't provide a string.
    • mlyle 6y ago
      The issue is: the two functions that we're comparing for correctness treat lengths very differently: one scans len-1 bytes, the other scans len+1 bytes. Even with a null terminator, there isn't a length that would work for both without overrunning the buffer. printf("%d %d\n", search_ok_1("mok", 2), search_ok_2("mok", 2)); printf("%d %d\n", search_ok_1("mok", 3), search_ok_2("mok", 3)); /* Overruns without null term */ printf("%d %d\n", search_ok_1("mok", 4), search_ok_2("mok", 4)); /* Overruns even WITH null term */ Prints out: 1 2 1 3 1 1
  • makapuf 6y ago
    Thats why strncpy is deprecated for strlcpy.
• billsnow 6y ago
  Oh I have some bad news for you, buddy.