In cases of multiple inheritance: Constructors are called in order of derivation, destructors in reverse order : multiple base classes « Class « C++ Tutorial

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2. Class
3. multiple base classes

#include <iostream>
using namespace std;
   
class base {
public:
  base() { cout << "Constructing base\n"; }
  ~base() { cout << "Destructing base\n"; }
};
   
class derived1 : public base {
public:
  derived1() { cout << "Constructing derived1\n"; }
  ~derived1() { cout << "Destructing derived1\n"; }
};
   
class derived2: public derived1 {
public:
  derived2() { cout << "Constructing derived2\n"; }
  ~derived2() { cout << "Destructing derived2\n"; }
};
   
int main()
{
  derived2 ob;
   
  // construct and destruct ob
   
  return 0;
}