In C++, constructors and destructors are essential for managing an object’s lifecycle. Constructors, named after their class, are automatically called when an object is created, allowing for initial setup with default or specific values. They can also be overloaded to support different initialization options.
Destructors, marked by a tilde (~) before the class name, are automatically invoked when an object is no longer needed. This ensures resources like memory and file handles are released, preventing resource leaks. Understanding these concepts—along with the types of constructors (default, parameterized, and copy constructors) and copying methods (shallow and deep copy)—enables developers to effectively control object behavior and resource management in C++.
Constructors are special member functions in C++ programming, they also bear the same name as their class. They are useful in controlling the lifecycle of an object for the simple reason that they are invoked whenever an object is created.
Naming Convention: Constructors are also called with the same name as the class and do not even return void.
Initialization: They are mainly used to assign default or user defined values to members of a class.
Overloading: In a class, it is possible to define more constructors which allow different creation of objects.
Access Specifiers: A constructor does not have any return type and can be made as public, private or protected, however the constructors are generally made public so that the objects can be created from outside the class.
Inheritance: Constructors are not the part of derived classes but a derived class can invoke a constructor of its own base class.
Addressing: In particular, the addresses of constructors cannot be referenced explicit.
Default Constructor:
This constructor does not accept any argument. In case of no constructors having been created, the compiler will automatically build a default constructor.
It allocates memory to objects and sets up with some or no values.
Parameterized Constructor:
This type permits one or more letters when creating an object, and the formed object is given some values at the time of its formation.
Copy Constructor:
The special constructor of this kind of classes allows to create a new object as a copy of another object which belongs to the same class.
It is called whenever an object is copied by value, created by a function or created by a constructor.
Shallow Copy:
Use for making a copy of member variables of an object and they puts these values in the new object which is created. However, if any member points to dynamically allocated memory it is identical with the original object.
Deep Copy:
Affected objects have their own copy of the data, so there will be a different copy of newly dynamically allocated memory.
Destructors
A destructor is a special member function of a class that is automatically invoked on an object when the object was destroyed or deleted. It has the name of the class but has a tilde (~) before its name.
Key Features of Destructors:
Automatic Invocation: It provides destructors, which automatically run when the object in discussion requires disposal or is deleted to eliminate resource hang around.
No Parameters or Return Type: Destructors do not take any parameter and it also does not give any sort of value.
Single Instance: A class can only have one destructor but it can have multiple overloaded forms of the destructor.
Resource Management: They are opened mainly to free objects for example, memory, file handles, or network connections.
Knowing about constructors and destructors will enable a programmer to have control of what is referred as resource leak in C++ as well as control the lifecycle of objects in a program.