Question

typedef struct temp   {           int a,b;           char  *c;           temp(){ c = (char*)malloc(10);};           ~temp(){free(c);};   }temp;    int main()   {      temp a;      list<temp>   l1;      l1.push_back(a);      l1.clear();      return 0;    }   

giving segmentation fault.

Answer 1

You don’t have a copy constructor.

When you push ‘a’ into the list, it gets copied. Because you don’t have a copy constructor (to allocate memory for c and copy from old c to new c) c is the same pointer in a and the copy of a in the list.

The destructor for both a’s gets called, the first will succeed, the second will fail because the memory c points to has already been freed.

You need a copy constructor.

To see whats happening, put some couts in the constructors and destructors and step through the code.