how much does the default destructor do

Question

Does the default destructor in C++ classes automatically delete members that are not explicitly allocated in code? For example:

class C {
  public:
    C() {}
           


        

Answer 1

If your class/struct contains a pointer, and you explicitly allocate something for that pointer to refer to, then you normally need to write a matching delete in the dtor. Members that are directly embedded into the class/struct will be created and destroyed automatically.

class X { 
    int x; 
    int *y;
public:
    X() : y(new int) {}
    ~X() : { delete y; }    
};

Here X::x will be created/destroyed automatically. X::y (or, to be technically correct, what X::y points at) will not -- we allocate it in the ctor and destroy it in the dtor.