Question

What is the order in which the destructors and the constructors are called in C++? Using the examples of some Base classes and Derived Classes

Answer 1

The order is:

1. Base constructor
2. Derived constructor
3. Derived destructor
4. Base destructor

Example:

class B { public:   B()   {       cout<<'Construct B'<<endl;   }    virtual ~B()   {     cout<<'Destruct B'<<endl;   } };  class D : public B { public:   D()   {       cout<<'Construct D'<<endl;   }    virtual ~D()   {     cout<<'Destruct D'<<endl;   } };    int main(int argc, char **argv) {   D d;    return 0; } 

Output of example:

Construct B

Construct D

Destruct D

Destruct B

Multiple levels of inheritance works like a stack:

If you consider pushing an item onto the stack as construction, and taking it off as destruction, then you can look at multiple levels of inheritance like a stack.

This works for any number of levels.

Example D2 derives from D derives from B.

Push B on the stack, push D on the stack, push D2 on the stack. So the construction order is B, D, D2. Then to find out destruction order start popping. D2, D, B

More complicated examples:

For more complicated examples, please see the link provided by @JaredPar