Forem: Harini

Understanding Constructor Functions in JavaScript

Harini — Thu, 09 Apr 2026 07:28:38 +0000

In JavaScript, a constructor function is used to create multiple objects with similar properties and methods. Instead of creating objects manually again and again, we use a constructor to generate them easily.

What is an Object?

An object stores data in key–value pairs.

Example:

let person = {
  name: "Harini",
  age: 22
};

Here:

name and age are keys
"Harini" and 23 are values If we want to create many similar objects, writing this structure repeatedly is not efficient. That’s why we use constructor functions.

What is a Constructor Function?

A constructor function is a normal function used to create objects.

By convention, constructor function names should start with a capital letter.
Example:

function User() {
  this.name = "Harini";
}

Here:

this refers to the newly created object.
this.name assigns a property to that object.

Creating an Object Using new
To create an object from a constructor, we use the new keyword.

let user1 = new User();
console.log(user1);

What happens when we use new?

When we write new User():

A new empty object is created.
this refers to that new object.
Properties are added to the object.
The object is returned automatically.

We do not need to manually write return this.

Creating Multiple Objects

Each time we use new, a new object is created.

let user1 = new User();
let user2 = new User();

Both user1 and user2 are separate objects.

Constructor with Arguments

Constructor functions can also accept parameters.

Example:

function User(name) {
  this.name = name;
}

let user1 = new User("Harini");
console.log(user1);

Now the value is passed dynamically instead of being hardcoded.
This makes the constructor more flexible.

Adding Properties and Methods
We can add both properties and methods inside a constructor.
Example:

function User(name, age) {
  this.name = name;
  this.age = age;
  this.getAge = function() {
    return this.age;
  };
}

let user1 = new User("Harini", 22);
console.log(user1.getAge());

Here:

name and age are properties.
getAge() is a method.
Methods are called using parentheses.

Important Points to Remember

Constructor function names should start with a capital letter.
Always use the new keyword to create objects.
this refers to the newly created object.
Each new call creates a separate object.

Learn ASCII with Easy Examples in Python and JavaScript

Harini — Wed, 08 Apr 2026 14:15:21 +0000

What is ASCII?

ASCII (American Standard Code for Information Interchange) is a character encoding system used to represent text in computers using numbers.

Each character—such as letters (A–Z, a–z), digits (0–9), and symbols (@, #, etc.)—is assigned a unique numeric value called an ASCII value.

Example

'A' → 65
'a' → 97
'1' → 49
'@' → 64

Why ASCII is Important

Helps computers store and process text
Used in programming and string manipulation
Foundation for modern encoding systems like Unicode

JavaScript

let name = "silambu9391a@gmail.com";

for (let i = 0; i < name.length; i++) {
    console.log(name[i] + " : " + name.charCodeAt(i));
}

How it works

name[i] -> gets the character
name.charCodeAt(i) -> gets ASCII value of that character

Python

name = "silambu9391a@gmail.com"

for ch in name:
    print(ch, ":", ord(ch))

How it works

for ch in name → loops through each character
ord(ch) → gives ASCII value of that character

Output

Method Overloading in Java

Harini — Wed, 08 Apr 2026 09:01:31 +0000

Method Overloading is a feature in Java where multiple methods have the same name but different parameters.

It helps improve code readability and allows you to use the same method name for different tasks.

Rules for Method Overloading
To overload a method, you must change at least one of the following:

Number of parameters
Type of parameters
Order of parameters

Changing only the return type is NOT allowed

Example 1: Different Number of Parameters

class Calci {

    public static void main(String[] args) {
        Calci obj = new Calci();

        System.out.println(obj.add(10, 20));      
        System.out.println(obj.add(10, 20, 30));  
    }

    int add(int a, int b) {
        System.out.println("2 arguments");
        return a + b;
    }

    int add(int a, int b, int c) {
        System.out.println("2 arguments");
        return a + b + c;
    }
}

Output

Example 2: Different Data Types

class Student {


    public static void main(String[] args) {
        Student obj = new Student();

        obj.show(100);
        obj.show("Harini");
    }

    void show(int a) {
        System.out.println("Integer: " + a);
    }

    void show(String a) {
        System.out.println("String: " + a);
    }
}

Output

Example 3: Order of Parameters

class Test {

    public static void main(String[] args) {
        Test obj = new Test();

        obj.print(10, "Java");
        obj.print("Hello", 20);
    }

    void print(int a, String b) {
        System.out.println(a + " " + b);
    }

    void print(String b, int a) {
        System.out.println(b + " " + a);
    }
}

Output

Step-by-Step Execution

Program starts from main() method
Object is created
Method is called
Java checks:
- Number of arguments
- Data type of arguments
Matching method is executed
Output is displayed

Methods Examples in Java

Harini — Wed, 08 Apr 2026 09:01:13 +0000

Void method(With return)

public class Display{
    public static void main(String[] args){
        Display casio = new Display();
        casio.add();

    }
    public void add(){
        return;
    }
}

Step-by-Step Execution

Program starts from main()
Display casio = new Display();
- A new object of class Display is created.
casio.add();
- The add() method is called.
Inside add():
- return; simply exits the method
- No value is returned because the method type is void
Program ends

Output

Mark Calculation Program

public class Marks{

    public static void main(String[] args){
        int total = sumMarks(100,98,78,95,91);
        int avg = average(total);
        grade(avg);
    }

    public static int sumMarks(int m1,int m2,int m3,int m4,int m5){
        int total = m1 + m2 + m3 + m4 + m5;
        return total;
    }

    public static int average(int total){
        int avg = total/5;
        return avg;
    }

    public static void grade(int avg){
        if(avg>=90){
            System.out.println("A");
         }
        else if(avg>=80){
            System.out.println("B");
         }
        else if(avg>=70){
            System.out.println("C");
         }
        else if(avg>=60){
            System.out.println("D");
         }
        else if(avg>=50){
            System.out.println("E");
         }
        else{
            System.out.println("Fail");
        }
    }
}

Step-by-Step Execution

The program starts from the main() method.
sumMarks(100,98,78,95,91) method is called.
Inside sumMarks():
- All marks are added → 462
- The value is returned to main()
average(total) method is called.
Inside average():
- Average is calculated → 462 / 5 = 92
- The value is returned to main()
grade(avg) method is called.
Inside grade():
Condition avg >= 90 is checked
"A" is printed
- The program ends successfully.

Output

String Manipulation in Python

Harini — Wed, 08 Apr 2026 08:59:33 +0000

What is a String?

A string is a sequence of characters used to store text in a program.

Characters can include:

Letters (A–Z, a–z)
Numbers (0–9)
Symbols (@, #, !, etc.)
Spaces

1. Accessing Characters in a String

Python

name = "Harini"

print(name[0])  # First character
print(name[-1]) # Last character
print(name[len(name)//2])  # Middle character

Explanation

name[0] -> First character -> H
name[-1] -> Last character -> i
len(name)//2 -> Finds the middle index
name[len(name)//2] -> Middle character -> i

Output

2. Convert String to Uppercase

Python

name = "Harini"

print(name.upper())

Explanation

upper() method converts the entire string into uppercase.

Output

3. Convert String to Lowercase

Python

name = "Harini"

print(name.lower())

Explanation

lower() method converts the entire string into lowercase.

Output

4. Convert First and Last Character to Uppercase

Python

name = "harini"

result = name[0].upper() + name[1:-1] + name[-1].upper()

print(result)

Explanation

name[0].upper() -> First character uppercase
name[1:-1] -> Middle part of the string
name[-1].upper() -> Last character uppercase

Output

5. Extracting Parts of a String

Python

name = "Harini"

length = len(name)

print(name[0].upper())                # First character
print(name[1:length//2])              # First half (excluding first char)
print(name[length//2].upper())        # Middle character
print(name[length//2+1:length])       # Second half
print(name[-1].upper())               # Last character

Output

Return Types in Java

Harini — Tue, 07 Apr 2026 16:12:34 +0000

What is a Return Type?

A return type is the data type of the value that a method sends back to the calling method.

Syntax

returnType methodName(parameters) {
    // code
    return value;
}

returnType → int, double, String, boolean, etc.
return value; → sends result back

Example 1: Returning an Integer

public class Example1 {

    public static void main(String[] args) {
        Example1 obj = new Example1();

        int result = obj.add(10, 5);
        System.out.println("Result = " + result);
    }

    int add(int a, int b) {
        return a + b;
    }
}

Output

Here:

Return type = int
Method returns an integer value

Flow of execution

main() method starts execution
Object obj is created
add(10, 5) method is called
Inside method → a + b is calculated
Value 15 is returned to main()
Stored in result and printed

Example 2: Returning a String

public class Example2 {

    public static void main(String[] args) {
        Example2 obj = new Example2();

        String message = obj.greet("Harini");
        System.out.println(message);
    }

    String greet(String name) {
        return "Hello " + name;
    }
}

Output

Flow of execution

main() starts
Object is created
greet("Harini") is called
Method creates "Hello Harini"
Returns string to main()
Printed on screen

Example 3: Returning a Boolean

public class Example3 {

    public static void main(String[] args) {
        Example3 obj = new Example3();

        boolean result = obj.isEven(4);
        System.out.println("Is Even? " + result);
    }

    boolean isEven(int number) {
        return number % 2 == 0;
    }


}

Output

Flow of execution

main() starts
Object is created
isEven(4) is called
Condition 4 % 2 == 0 checked
Returns true
Printed as result

Example 4: void Return Type

public class Example4 {

     public static void main(String[] args) {
        Example4 obj = new Example4();

        obj.display();   // calling method
    }

    void display() {
        System.out.println("Hello");
    }


}

Output

Flow of execution

main() starts
Object is created
display() is called
Method directly prints "Hello"
No value returned

Understanding Methods in Java with Simple Example

Harini — Tue, 07 Apr 2026 05:09:51 +0000

What is a Method in Java?

A method in Java is a block of code that performs a specific task.
It helps you reuse code, improve readability, and organize programs.

Basic Syntax

returnType methodName(parameters) {
    // method body
    // code to execute
    return value; // optional
}

Example Program

public class Calculator{
    public static void main(String[] args){
        Calculator casio = new Calculator();
        casio.add(10,5);
        casio.sub(10,5);
        casio.multiply(10,5);
        casio.div(10,5);
    }
    void add(int a,int b){
        System.out.println(a+b);
    }
    void sub(int a,int b){
        System.out.println(a-b);
    }
    void multiply(int a,int b){
        System.out.println(a*b);
    }
    void div(int a,int b){
        System.out.println(a/b);
    }
}

Output

Flow of Execution

Program starts in main()
Object casio is created
Methods are called one by one:
- add() → prints 15
- sub() → prints 5
- multiply() → prints 50
- div() → prints 2
Program ends

Types of Methods in Java
1. Predefined Methods

These are already available in Java libraries.

Example:

System.out.println("Hello");

Here, println() is a predefined method.

2. User-defined Methods

Methods created by the programmer.

Example:

int add(int a, int b) {
    return a + b;
}

Global Variables vs Local Variables in Java

Harini — Mon, 06 Apr 2026 10:54:39 +0000

When learning Java, one of the most important concepts to understand is how variables work. Among them, global variables and local variables play a key role in writing efficient and clean programs.

In this blog, we’ll break down these concepts in a simple and beginner-friendly way.

What Are Global Variables in Java?

Global variables in Java are variables that are declared inside a class but outside any method. They can be accessed by all methods within that class.

Types of Global Variables

Non-Static Variables(Instance) – Belong to an object
Static Variables – Shared across all objects

Example

class Demo {
   int x = 10;        // Instance variable
   static int y = 20; // Static variable

   void display() {
     System.out.println(x);
     System.out.println(y);
   }

   public static void main(String[] args) {
       Demo obj = new Demo(); // create object
       obj.display();         // call method
   }
}

Output

Step-by-step flow

main() starts execution
Object is created → Demo obj = new Demo();
display() method is called
Prints: 10 20

Key Characteristics

Declared inside the class, outside methods
Accessible throughout the class
Automatically assigned default values
Longer lifetime (until object or class exists)

What Are Local Variables in Java?

Local variables are declared inside a method, constructor, or block and can only be used within that specific area.

Example

class Demo {
    void display() {
        int a = 5;
        System.out.println(a);
    }

    public static void main(String[] args) {
        Demo obj = new Demo(); // create object
        obj.display();         // call method
    }
}

Output

Step-by-step flow

main() starts execution
Object is created
display() is called
Output: 5

Key Characteristics

Declared inside methods or blocks
Limited scope (only within method)
No default values (must be initialized)
Short lifetime (exists only during execution)

Python vs Java vs JavaScript: Complete Beginner-Friendly Comparison

Harini — Mon, 06 Apr 2026 06:32:15 +0000

What is Python?

Python is a high-level programming language known for its simplicity and readability. Its clean syntax makes it one of the best choices for beginners.

Key Features

Easy-to-learn and readable syntax
Dynamically typed (no need to declare variable types)
Huge ecosystem of libraries and frameworks
Interpreted language (runs line by line)

Common Use Cases

Data Science & Machine Learning
Artificial Intelligence
Automation & scripting
Web development (Django, Flask)

What is Java?

Java is a robust, object-oriented programming language widely used in enterprise-level applications.

Key Features

Strongly typed language
Platform independent (Write Once, Run Anywhere)
Highly secure and scalable -Runs on the Java Virtual Machine (JVM)

Common Use Cases

Enterprise applications
Banking and financial systems
Android app development
Large backend systems

What is JavaScript?

JavaScript is the backbone of web development, used to create dynamic and interactive web pages.

Key Features

Runs directly in web browsers
Event-driven and asynchronous
Dynamically typed
Can be used for both frontend and backend (Node.js)

Common Use Cases

Frontend web development
Interactive UI elements (animations, forms)
Real-time applications (chat apps, live updates)
Backend development (Node.js)

Programming Language vs Scripting Language

Harini — Mon, 06 Apr 2026 06:30:38 +0000

In the world of software development, the terms programming language and scripting language are often used interchangeably. However, they have distinct purposes, execution methods, and use cases.

Let’s break it down in a simple and clear way.

What is a Programming Language?
A programming language is a formal language used to write instructions that a computer can execute. These languages are typically compiled before execution.

Key Features:

Requires compilation (converted into machine code)
Faster execution
Used for building full-scale applications
More control over hardware Examples:
C
C++
Java Use Cases:
Operating systems
Desktop applications
Game development

What is a Scripting Language?

A scripting language is designed to automate tasks and is usually interpreted rather than compiled.

Key Features:

No need for compilation
Runs line-by-line (interpreted)
Slower compared to compiled languages
Easier and quicker to write

Examples:

Python
JavaScript
PHP

Use Cases:

Web development
Automation scripts
Backend services

Unlocking the Logic Behind Neon, Strong & Perfect Numbers

Harini — Sat, 04 Apr 2026 04:38:57 +0000

1. Neon Number
A Neon Number is a number where:

Sum of digits of its square = the number itself

Example:
Number = 9
Square = 81
Sum = 8 + 1 = 9

So, 9 is a Neon Number.

Key Logic:

Find square of number
Extract digits
Add digits
Compare with original number

Python

def neon_no(no):
    sqr = no * no
    res = sqr
    sum = 0

    while res > 0:
        sum = sum + res % 10
        res = res // 10

    if sum == no:
        print("Neon")
    else:
        print("Not Neon")


neon_no(9)

JavaScript

function neonNo(no) {
    let sqr = no * no;
    let res = sqr;
    let sum = 0;

    while (res > 0) {
        sum = sum + (res % 10);
        res = Math.floor(res / 10);
    }

    if (sum === no) {
        console.log("Neon");
    } else {
        console.log("Not Neon");
    }
}

neonNo(9);

Java

public class Main {
    public static void neonNo(int no) {
        int sqr = no * no;
        int res = sqr;
        int sum = 0;

        while (res > 0) {
            sum = sum + (res % 10);
            res = res / 10;
        }

        if (sum == no) {
            System.out.println("Neon");
        } else {
            System.out.println("Not Neon");
        }
    }

    public static void main(String[] args) {
        neonNo(9);
    }
}

Output

2. Strong Number
A Strong Number is a number where:

Sum of factorial of digits = the number itself

Example:
Number = 145
Factorials = 1! + 4! + 5!
= 1 + 24 + 120 = 145

So, 145 is a Strong Number.

Key Logic:

Extract each digit
Find factorial
Add all factorials
Compare with original number

Python

def factorial(n):
    if n==1:
        return 1
    return n*factorial(n-1)

def strong(num):
    numc=num
    sum=0
    while  numc>0:
        sum=sum+factorial(numc%10)
        numc=numc//10
    if sum==num:
        print( num," is strong")
    else:
        print( num," is not strong")

strong(145)

JavaScript


function factorial(n) {
    if (n === 0 || n === 1) {
        return 1;
    }
    return n * factorial(n - 1);
}

function strong(num) {
    let numc = num;
    let sum = 0;

    while (numc > 0) {
        let digit = numc % 10;
        sum = sum + factorial(digit);
        numc = Math.floor(numc / 10);
    }

    if (sum === num) {
        console.log(num + " is strong");
    } else {
        console.log(num + " is not strong");
    }
}

strong(145);

Java

public class StrongNumber {

    // Factorial function (recursion)
    public static int factorial(int n) {
        if (n == 0 || n == 1) {
            return 1;
        }
        return n * factorial(n - 1);
    }

    // Strong number check
    public static void strong(int num) {
        int numc = num;
        int sum = 0;

        while (numc > 0) {
            int digit = numc % 10;
            sum = sum + factorial(digit);
            numc = numc / 10;
        }

        if (sum == num) {
            System.out.println(num + " is strong");
        } else {
            System.out.println(num + " is not strong");
        }
    }

    public static void main(String[] args) {
        strong(145);
    }
}

Output

3. Perfect Number

A Perfect Number is a number where:

Sum of its proper divisors = the number itself

Example:
Number = 6
Divisors = 1, 2, 3
Sum = 1 + 2 + 3 = 6

So, 6 is a Perfect Number.

Key Logic:

Find all divisors (except the number itself)
Add them
Compare with original number

def divisor_sum(no):
    sum = 0
    div = 1

    while div < no:
        if no % div == 0:
            sum += div
        div += 1

    return sum


def perfect_no(no):
    if divisor_sum(no) == no:
        print("Perfect")
    else:
        print("Not Perfect")


perfect_no(6)

JavaScript

function divisorSum(no) {
    let sum = 0;
    let div = 1;

    while (div < no) {
        if (no % div === 0) {
            sum += div;
        }
        div++;
    }

    return sum;
}

function perfectNo(no) {
    if (divisorSum(no) === no) {
        console.log("Perfect");
    } else {
        console.log("Not Perfect");
    }
}

perfectNo(6);

Java

public class Main {

    public static int divisorSum(int no) {
        int sum = 0;
        int div = 1;

        while (div < no) {
            if (no % div == 0) {
                sum += div;
            }
            div++;
        }

        return sum;
    }

    public static void perfectNo(int no) {
        if (divisorSum(no) == no) {
            System.out.println("Perfect");
        } else {
            System.out.println("Not Perfect");
        }
    }

    public static void main(String[] args) {
        perfectNo(6);
    }
}

Output

Number Pattern Programs

Harini — Fri, 03 Apr 2026 05:03:21 +0000

1. 5 6 3 4 1 2

num = int(input("Enter number: "))
rev = 0

while num > 0:
    rev = rev * 100 + num % 100
    num = num // 100

print("Reverse =", rev)

Output

2. 4 5 6 1 2 3

num = int(input("Enter number: "))
rev = 0

while num > 0:
    rev = rev * 1000 + num % 1000
    num = num // 1000

print("Reverse =", rev)

Output

3. 1 3 5 2 4 6

no = 123456
no1 = 100000
result1 = ""  
result2 = ""  

while no > 0 and no1 >= 1:
    res = no // no1
    res1 = res % 10
    result1 += str(res1)      
    no = no % no1
    no1 = no1 // 10           

    if no > 0 and no1 >= 1:
        res = no // no1
        res2 = res % 10
        result2 += str(res2)  
        no = no % no1
        no1 = no1 // 10

result = result1 + result2
print(result)

4. EMIRP

def prime(no):
    div=2
    while div< no/2:
        if no%div==0:
            return False
        div+=1
    return True

def reverse(no):
    rev=0
    while no>0:
        rev=rev*10+no%10
        no=no//10
    return rev

num=17
if prime(num) and prime(reverse(num)):
    print(num,"is emirp")
else:
    print(num,"is not emirp")

Output