Constructors, Destructors and Inheritance in C++

It is possible for a base class, a derived class, or both to contain constructor and destructor functions. It is important to understand the order in which these functions are executed when an object of a derived class comes into existence and when it goes out of existence. To begin, examine this short program:

#include <iostream>
using namespace std;
class base {
public:
base() { cout << "Constructing base\n"; }
~base() { cout << "Destructing base\n"; }
};

class derived: public base {
public:
derived() { cout << "Constructing derived\n"; }
~derived() { cout << "Destructing derived\n"; }
};

int main()
{
derived ob;
return 0;
}

In cases of multiple inheritances, the general rule applies: Constructors are called in order of derivation, destructors in reverse order. Example:
#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;
return 0;
}