C++ constructors initialize objects and provide data when objects are created. There are three types of constructors: default constructors which have no parameters, parameterized constructors which initialize objects with different values, and copy constructors which initialize a new object using an existing object of the same class. Destructors destroy objects and free memory when objects go out of scope or are destroyed. Destructors have the same name as the class preceded by a tilde and are automatically called when objects are destroyed.

1. C++ Constructor

2. Definition
• In C++, constructor is a special method which is
invoked automatically at the time of object creation.
• It constructs the values i.e. provides data for the object
Hence it is known as constructors.
• The constructor in C++ has the same name as class.
• Constructor does not have a return value, hence they do
not have a return type.

3. There can be two types of constructors in C++.
• Default constructor
• Parameterized constructor
• Copy Constructor

4. Default Constructor
• A constructor which has no argument is known
as default constructor.
• It is invoked at the time of creating object.
Note: Attend class for examples

5. Parameterized Constructor
• A constructor which has parameters is called
parameterized constructor.
• It is used to provide different values to distinct
objects.
Note: Attend class for examples

6. Copy Constructor
• A copy constructor initializes an object using another object of the
same class.
• A copy constructor has the following general function prototype:
ClassName (const ClassName &old_obj);
• Copy constructor is used to initialize the members of a newly
created object by copying the members of an already existing object.
• Copy constructor takes a reference to an object of the same class as
an argument.
Sample(Sample &t)
{
id=t.id;
}

7. • The process of initializing members of an object through a copy
constructor is known as copy initialization.
• It is also called member-wise initialization because the copy
constructor initializes one object with the existing object, both
belonging to the same class on a member by member copy basis.
• The copy constructor can be defined explicitly by the programmer.
If the programmer does not define the copy constructor, the
compiler does it for us.

8. Destructors
• Destructor is an instance member function
which is invoked automatically whenever an
object is going to be destroyed.
• Meaning, a destructor is the last function that
is going to be called before an object is
destroyed.

9. • Destructor is also a special member function like
constructor.
• Destructor destroys the class objects created by constructor.
• Destructor has the same name as their class name preceded
by a tilde (~) symbol.
• It is not possible to define more than one destructor.
• The destructor is only one way to destroy the object created
by constructor. Hence destructor can-not be overloaded.

10. • Destructor neither requires any argument nor
returns any value.
• It is automatically called when object goes out of
scope.
• Destructor release memory space occupied by the
objects created by constructor.
• In destructor, objects are destroyed in the reverse
of an object creation.

11. • Codes are discussed in class, refer from there.