What is the order in which the destructors and the constructors are called in C++

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

A detailed description of these events, including virtual and multiple inheritance is available at the C++ FAQ Lite. Section 25.14 and 25.15

https://isocpp.org/wiki/faq/multiple-inheritance#mi-vi-ctor-order

Also, keep in mind that while array elements are constructed first -> last, they are destructed in the reverse order: last -> first.

This is clearly described at order-dtors-for-members. Basically, the rule is "First constructed, last destructed."

Constructors calling order:

1. base's constructors are called in the order of appearance after the ":"
2. derived class member's constructors are called in the order of appearance and before class's constructor

Destructors are called in reversed order of called constructors.

Example:

#include <iostream>

struct base0 {  base0(){printf("%s\n", __func__);};~base0(){printf("%s\n", __func__);}; };
struct base1 { base1(){printf("%s\n", __func__);}; ~base1(){printf("%s\n", __func__);};};
struct member0 { member0(){printf("%s\n", __func__);};  ~member0(){printf("%s\n", __func__);};};
struct member1 { member1(){printf("%s\n", __func__);}; ~member1(){printf("%s\n", __func__);};};
struct local0 { local0(){printf("%s\n", __func__);}; ~local0(){printf("%s\n", __func__);}; };
struct local1 { local1(){printf("%s\n", __func__);};  ~local1(){printf("%s\n", __func__);};};
struct derived: base0, base1
{
  member0 m0_;
  member1 m1_;
  derived()
  {
    printf("%s\n", __func__);
    local0 l0;
    local1 l1;
  }
  ~derived(){printf("%s\n", __func__);};
};
int main()
{
  derived d;
}

Output:

base0
base1
member0
member1
derived
local0
local1
~local1
~local0
~derived
~member1
~member0
~base1
~base0