DEV Community: Pushpender Singh

C++ - Operator Overloading

Pushpender Singh — Mon, 30 Dec 2019 10:14:59 +0000

What is it?

Giving the normal C++ operators such as +, -, ++, *, additional meaning when they are applied to user defined type such as class.

But why?

Let's say we have created a class called counter.

class Counter
{
private:
    int count;

public:
    Counter() : count(0) {}

    void inc_Count()
    {
        count++;
    }
};

And a object of class Counter name c1

Counter c1;

So in this case if we want to increment count variable, we have to call inc_Count() member function.

Like this:

c1.inc_count();

Don't you think it would be great if we can just do this:-

c1++; // Postfix

// or

++c1; // Prefix

If yes, then Operator Overloading can help us.

Overload "++"

This operator can be use in two notation:-

Prefix - first operator then variable/object
Postfix - first variable then operator

Note:- In our example it doesn't matter, both Prefix or Postfix have same effect.

Let's explore Prefix first

Prefix

Add this into class Counter under Public:

void operator ++ () {
    ++count;
}

To overload an operator we create a member function with operator keyword.

void is return type
operator is keyword
++ is an operator
() are parenthesis with no parameters
{} are curly braces - it is function body

Now you can do this:-

++c1;

Postfix

Add this into class Counter under Public:

void operator ++ (int) {
    count++;
}

Only difference between Prefix and Postfix is, in Postfix we specify int in () parenthesis (because how C++ Compiler know we want to do Prefix or Postfix) and in function body

Now you can do this:-

c1++;

You can do same with --

Warning

You can't overload ::, ., ->, ?: operators.
You can't create new ones.

There is more if you want to learn, follow this pdf

That's it guys.
Have a nice day.

If you find anything incorrect or know more about it let me know in the comments.

C++ - Objects & Classes

Pushpender Singh — Thu, 19 Dec 2019 07:31:31 +0000

Class

Class is a user defined datatype.
It contains variables and functions.
It is used to create Objects.

Think of it like a blueprint.

Object

It is instance of a class.
One class can create as many objects.
It represents real world entity.
sometime called instance variable.

Analogy

Let's you are an architect and you designed a blueprint of a house. Your designed blueprint is amazing that so many people want to make house out of it. So you show them your blueprint. Finally everyone have their dream houses. In this case your blueprint is called class and houses are called objects.

Some Formal Terms

Variable in Object = Member Data
Function in Object = Member Function

(Note:- some programming languages, member functions called methods.)

How to define class?

class className {
private:
    // Member Data
    int a;

public:
    // Member Function
    void showdata() {  
    std::cout << a << std::endl;
   }
};

// private and public are called access modifiers.

How to create Object?

className objectName;

Calling Member Function

objectName.showdata();

/* Here "dot" in between object and member function
called "class member access operator".
*/

Constructor

A Constructor is a member function that is executed automatically whenever an object is created.

How to define a Constructor?

class className {
public:
    classname() {
    // constructor body
  }
};

/*
1. It must be same name as class name.
2. It have no return type.
*/

Destructor

A Destructor is a member function that is executed automatically whenever an object is destroyed.

How to define a Destructor?

class className {
public:
    ~classname() {
    // Destructor body
  }
};

/*
1. It must be same name as class name.
2. It have no return type.
*/

References:-

That's it guys.

If you find anything incorrect or know more about it let me know in the comments.

C++ - Variables

Pushpender Singh — Sun, 15 Dec 2019 07:48:21 +0000

A variable in simple terms is a storage place which has some memory allocated to it.

Think of it like a box where you can put your data into.

Terms

Declaration:- specify variable name and it’s data type.
Definition:- Declaration + assign memory to it.
Initialization:- put value into the box.
Datatype:- size of the box
Variable Name: name of the box.

How to Create a Variable?

First Method

int a = 12;

/*
int = datatype
a = variable name
12 = value
*/

Second Method

int a{12}; // called uniform initialization

Third Method

int a(12); // called constructor initialization

Note:- All these three called definition + initialization of a variable.

References for more information:-

That's it guys. Have a good day.

If you find anything incorrect or know more about it let me know in the comments.

C++ - The Introduction

Pushpender Singh — Mon, 02 Dec 2019 10:51:25 +0000

What is C++?

C++ is the Programming Language use to create computer programs.

It is a Cross Platform Language means programs made in c++ are able to run on different platforms like Windows/Linux etc with no or little modifications.

It was developed by Bjarne Stroustrup at Bell labs in 1979.

It is a Object Oriented Language (Note:- will discuss about it).

How to Create Programs in C++?

To do that we need :-

Hard way

Text Editor :- Where you type code. It could be Notepad but VSCode will be better.
Compiler:- who convert our file into computer's understandable form.

Note:- file extension should be .cpp and compiler will be according to your platform (Windows/Linux etc).

Easy Way

Just download one of these softwares:-

DevC++ (Link)
Code::Blocks (Link)

Note:- These are called IDEs (Integrated Development Environment).
Simply put Text Editor + Compiler = IDE.

Super Easy way

There are Online C++ Compilers:-

#Important terms

Source File :- File you create with text editor.
Executable File :- File that computer can understand/run directly.
Compilation :- Process of converting source file into Executable file.

That's it for today.

If you find anything incorrect or know about it let me know in the comments it would be really appreciated.

Bye Guys Have a good day.

My Intro!!

Pushpender Singh — Sun, 01 Dec 2019 07:16:06 +0000

Hello DEVs,

My name is Pushpender Thakur (nickname Piyush). I am a Student.
Currently pursuing B.C.A from Pt. J.L.N Govt College, Faridabad.

I am starting to learn C++. So i have an idea that as i learn i will create post about the topics i'll learn.
If you guys have more ideas about it. Let me know in the comments

So this is it.
thank you guys for your time