Destructors in a Class | C++ Object Oriented Tutorial

Summary

In this C++ programming tutorial by Anil, viewers are introduced to destructors, the counterpart to constructors. Destructors are special member functions executed when an object goes out of scope or is deleted, ensuring proper resource cleanup. The tutorial demonstrates creating a 'Human' class with both a constructor and destructor, using the 'new' keyword to create an object and 'delete' to deallocate its memory, illustrating the sequence of constructor and destructor calls. Anil emphasizes the importance of destructors in managing memory and their restrictions, such as no parameters or return values, before concluding with a reminder to subscribe for more educational content.

Takeaways

• 📘 The script is a C++ programming tutorial focused on destructors.
• 🔨 Destructors in C++ are special member functions that execute when an object goes out of scope or is deleted.
• 👉 Destructors are the opposite of constructors, which are called when an object is created.
• 📝 The destructor is declared with the `~` symbol followed by the class name and has no parameters or return values.
• 👷‍♂️ The tutorial demonstrates creating a class named 'human' with both a constructor and a destructor.
• 💬 The destructor is used to execute statements before the object's memory is released.
• 🔑 The scope resolution operator can be used to define the destructor outside the class.
• 🗑️ Demonstration includes creating an object with the 'new' keyword and deleting it to trigger the destructor.
• 🔄 When an object is created, the constructor is called, and when it's destroyed, the destructor is called.
• 🛠️ The tutorial includes a practical example of creating and deleting an object to illustrate the use of destructors.
• 👋 The presenter encourages viewers to subscribe for more tutorials and ends with a reminder for the next session.

Q & A

What is the purpose of a destructor in C++?

A destructor in C++ is a special member function of a class that is executed whenever an object of its class goes out of scope or when the delete expression is applied to a pointer to the object. It is used to release the memory allocated for the object and perform any necessary cleanup before the object is destroyed.

How is a destructor different from a constructor in C++?

A constructor is a special member function that is called when a new object of a class is created, while a destructor is called when an object is about to be destroyed. Unlike constructors, destructors cannot take parameters and cannot return any values.

What symbol is used to declare a destructor in C++?

The tilde symbol (~) is used to declare a destructor in C++, followed by the class name and a pair of parentheses.

Can a destructor be defined outside the class using the scope resolution operator?

Yes, a destructor can be defined outside the class using the scope resolution operator, which is the double colon (::).

What happens when an object is created using the 'new' keyword in C++?

When an object is created using the 'new' keyword in C++, the constructor of the class is called to initialize the object, and memory is allocated for it.

What is the role of the 'delete' keyword in C++?

The 'delete' keyword in C++ is used to deallocate the memory that was previously allocated for an object using the 'new' keyword. It also calls the destructor of the object.

What is the correct syntax for defining a destructor in a C++ class?

The correct syntax for defining a destructor in a C++ class is to use the tilde symbol (~), followed by the class name, a pair of parentheses, and then the body of the destructor enclosed in curly braces.

When is the destructor called for an object created within a function scope?

The destructor for an object created within a function scope is called when the function execution is completed and the object goes out of scope.

Can destructors have parameters or return values?

No, destructors in C++ cannot have parameters and cannot return any values. They are meant for cleanup and releasing resources.

What is the significance of the 'see out and' statement used in the destructor example?

The 'see out and' statement in the destructor example is likely a placeholder for a more meaningful action or message that should be executed or displayed when the destructor is called. It serves as a demonstration of where such actions would occur.

How can you observe the effect of a destructor in a C++ program?

You can observe the effect of a destructor in a C++ program by creating an object, running the program to see the constructor message, then deleting the object or allowing it to go out of scope and observing the destructor message.

Outlines

00:00

📚 Introduction to C++ Destructors

Anil introduces a C++ programming tutorial focused on destructors, explaining that they are special member functions executed when an object goes out of scope or is deleted. He contrasts this with constructors, which are called when objects are created. The tutorial aims to demonstrate the use of destructors by building a 'Human' class with both a constructor and a destructor. The destructor is declared with a tilde prefix and the same name as the class, and it cannot take arguments or return values. Anil also mentions the option to define the destructor outside the class using the scope resolution operator.

Keywords

💡Destructors

Destructors in C++ are special member functions of a class that are automatically called when an object of that class is about to be destroyed. They are crucial for managing resources, such as memory, that were allocated during the object's lifetime. In the video, the concept of destructors is introduced as the opposite of constructors, with the script demonstrating how a destructor is declared and called when an object goes out of scope or is deleted.

💡Constructors

Constructors are special member functions in C++ that are called when an object is created. They are used to initialize the object's member variables. The script mentions constructors as a prerequisite knowledge for understanding destructors, highlighting that constructors are called at the creation of an object, while destructors are called at its destruction.

💡Class

A class in C++ is a blueprint for creating objects, providing a way to encapsulate data and functionality together. The script uses the class 'human' as an example to demonstrate the use of both constructors and destructors, showing how they are defined within the class and how they relate to object lifecycle management.

💡Object

In the context of C++, an object is an instance of a class. The script explains the lifecycle of an object, from its creation via a constructor to its destruction via a destructor. The example given in the script involves creating an object of the 'human' class and then demonstrating the destructor's role when the object is deleted.

💡Scope

Scope in C++ refers to the visibility and lifetime of variables within the code. When an object goes out of scope, it is no longer accessible, and its destructor is called to perform cleanup operations. The script mentions that destructors are called not only when an object is explicitly deleted but also when it goes out of scope.

💡Pointer

A pointer in C++ is a variable that stores the memory address of another variable. In the script, a pointer named 'Anil' is used to demonstrate dynamic memory allocation with the 'new' keyword and deallocation with the 'delete' keyword, showing how destructors are called in the process.

💡Memory Allocation

Memory allocation in C++ is the process of reserving memory for storing data. The script explains how constructors are called when memory is allocated for a new object, and destructors are called when that memory is released, emphasizing the importance of proper resource management.

💡Delete Expression

The 'delete' keyword in C++ is used to deallocate dynamically allocated memory, effectively destroying the object and invoking its destructor. The script demonstrates the use of 'delete' with a pointer to show how the destructor is called to clean up after the object is no longer needed.

💡Tilde Symbol (~)

The tilde symbol is used in C++ to declare a destructor. It is placed before the class name to indicate that the function being defined is a destructor. The script mentions this symbol as part of the syntax for declaring a destructor within the 'human' class example.

💡Scope Resolution Operator (::)

The scope resolution operator '::' in C++ is used to specify that a name refers to a member of a particular namespace or class. The script suggests that destructors can be defined outside the class using this operator, which helps in clarifying the association between the destructor and the class it belongs to.

💡Video Tutorial

The script is part of a video tutorial series on C++ programming, specifically focusing on the concept of destructors. The term 'video tutorial' encapsulates the format and purpose of the content, which is to educate viewers on programming concepts through a visual and auditory medium.

Highlights

Introduction to the concept of destructors in C++ programming.

Relates destructors to constructors, explaining their opposite roles in object lifecycle.

Destructors are special member functions executed when an object goes out of scope or is deleted.

Demonstration of building a class named 'human' with a constructor and destructor.

Syntax explanation for declaring a destructor using the tilde symbol and class name.

Destructors cannot take arguments or return values, unlike constructors.

Option to define the destructor outside the class using the scope resolution operator.

Example of writing statements within the destructor to execute before object destruction.

Illustration of creating an object of the 'human' class using the 'new' keyword.

Observation that the destructor is not called immediately after object creation.

Demonstration of calling the destructor by deallocating memory with the 'delete' keyword.

Explanation of when the destructor is called: after object destruction or when going out of scope.

Clarification that destructors have the same name as the class and cannot return values or take parameters.

Emphasis on the importance of destructors in managing memory allocation and deallocation.

Encouragement for viewers to subscribe for more tutorials on C++ programming.

Closing remarks and anticipation for the next tutorial in the series.

Transcripts

hi this is Anil and welcome to the video

tutorial for the learning lad on C++

programming so in this tutorial we're

going to learn about the destructors in

C++ so I believe that you know all of

you guys have watched my previous

tutorials where you know I have

explained about the constructors in C++

you know a Constructor is a special

member function of a class that is

executed whenever we create new objects

of the class but this Destructor are

opposite to that a Destructor is also a

special member function of a class that

is executed whenever an object of its

class goes out of scope or whenever the

delete expression is applied to your

pointer to the object of that class

which is nothing but when we create an

object The Constructor will be called

and when the memory allocated for that

object will be released at that time the

destructor will be called

so here in this tutorial to demonstrate

the use of destructors we're going to

build a class so it's going to be class

hum and here we're going to write the

access specifier as public and let's

create a

Constructor you know the same name as a

class name and within this Constructor

we're going to specify Constructor

called and just end this line and next

we're going to write a special member

function which is the destructor to

declare a Destructor first we need to

use the til symbol the one which is

present above the tab key in your

keyboard and then the class name same as

the constructors here in this case it's

going to be

human and then a pair of parenthesis and

then a pair of curly braces and between

these curly braces we're going to write

the statements that we want to execute

before releasing all the memory

allocated for object the statements

inside this Destructor will be executed

before destroying the object so here

this Destructor cannot take any

arguments and it cannot return any

values but you know the constructors can

take parameters you know which we have

learned in previous tutorials and also

if you want to Define this Destructor

using the scope resolution operator

outside this class you guys can do that

you know and now we're going to write

the statements and just for the

demonstration purpose we're going to use

the see out and and we're going to say

Destructor

called and let's end this

line all right now we have created a

class with Constructor and destructors

the next thing that we're going to do is

we're going to create an object of this

class and here in this case we're going

to use the second method you know where

we are using the new keyword so first we

need a pointer it's going to be human

and and Then star let's say Anil and

then we're going to create an object

using the new is going to be Anil equal

to new

human and no parameters okay now I'm

going to save this I'm going to build

and run this you guys can see the

Constructor called and you know the

destructor is not called that's because

at this moment also the object is

present in the memory you know which is

not destroyed you know the destructor

will be called when the object is being

destroyed that's why what do we're going

to do is we're going to close this one

and uh we're going to use the delete

keyword to deallocate the memory

allocated for this object so it's going

to be

delete and then the pointer Anil and uh

I'm going to save this I'm going to

build and run this now you guys can see

Constructor called and then the

destructor called okay I spelled it

wrong no problem so what we can say is

you know when we create an object the

Constructor will be called and when we

destroy an object using the delete

keyword or you know when uh the function

that contains the object or where the

object created goes out of scope you

know that object will be destroyed at

that time the destructor will be called

a Destructor is a special member

function which has the same name as the

class name and this Destructor cannot

return any values and also we can't pass

any parameters to the destructor so

thank you for watching guys don't foret

to subscribe and I'll see you in the

next tutorial