cplusplusquestion@gmail.com wrote:

> On Sep 5, 9:06 pm, Barry <dhb2...@gmail.com> wrote:
>> Barry wrote:
>> > cplusplusquest...@gmail.com wrote:
>> >> #include <iostream>
>> >> #include <list>
>>
>> >> using namespace std;
>>
>> >> struct Cell{
>> >> list<int> vertices;
>> >> bool counted;
>> >> Cell* nextCell;
>> >> Cell(){
>> >> counted=false;
>> >> nextCell=NULL;
>> >> }
>> >> ~Cell(){
>> >> Cell* tmp = nextCell;
>> >> Cell* current_ptr = nextCell;
>> >> while(tmp != NULL){
>> >> current_ptr = current_ptr->nextCell;
>> >> delete tmp;
>>
>> > free(tmp);
>>
>> > calling delete will recursively call you ~Cell() and
>> > std::vector<int>::~vector()
>>
>> >> tmp = current_ptr;
>> >> }
>> >> }
>> >> };
>>
>> >> int main(){
>> >> Cell* a = new Cell;
>> >> Cell* b = new Cell;
>> >> Cell* c = new Cell;
>> >> a->nextCell = b;
>> >> b->nextCell = c;
>> >> delete a;
>> >> return 0;
>> >> }
>>
>> >> It compiles, but run the program, gets segmentation fault. If there is
>> >> no list<int> vertices, it will be fine. Or if no coding in destructor
>> >> and keep list<int> vertices, it's no problem too. Any idea?
>>
>> > so you're destructing vertices more than once within one Cell
>>
>> > std::vector<int> helping detect the error
>>
>> sorry, list<int>
>> and moreover, if use *free* other than *delete*, then /vertices/ won't
>> be destructed, which causes memory leak
>>
>> --
>> Thanks
>> Barry
>
> Thanks! Does that mean I need to malloc() for each object instead of
> new?

No, it means you have to fix the code in the destructor. Try:

~Cell(){
delete nextCell;
}


Best

Kai-Uwe Bux