3 ms·

I can't see why the code from akkartik would segfault when entry is NULL? What am I missing?

• Nursie 10y ago
  If entry and head are null, segfault on line 4. If entry is null and head is valid segfault on line 10. --edit-- As pointed out by my esteemed colleagues below, I didn't read the loop conditional properly. Only the first fault applies
  • A1kmm 10y ago
    > If entry is null and head is valid segfault on line 10. To get to line 10, we need prev->next == entry. Since we are talking about the case where entry == NULL, that requires prev->next == NULL The for loop condition is prev->next, which will fail if prev->next == NULL, hence line 10 would never be reached in that case. The difficulty of analysing all of this shows why mutable structures and variables make code hard to follow - perhaps the real good taste solution is to use something like finger trees instead of linked lists, together with a language which eliminates null.
  • jakobegger 10y ago
    How can you reach line 10 when entry is NULL? (prev->next==entry) can only be true at the end of the list, but the for-condition already checks that.