Understanding Programming

Who Writes or Creates Applications?

Definition: A programmer is a professional who writes and creates software applications using one or more programming languages. Programmers are often referred to as Software Developers.

Examples & Use Cases:

• A web developer writes code in JavaScript, HTML, and CSS to create websites.
• A game developer uses C++ to build 3D games.
• A mobile app developer uses Swift or Kotlin to develop smartphone applications.

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What is a Program?

Definition: A program is a structured set of instructions written in a specific sequence to perform a particular task or solve a problem.

Examples & Use Cases:

• A weather application fetching real-time data and displaying it.
• A calculator app executing arithmetic operations based on user input.
• A chatbot using AI to answer customer queries.

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Sequence Organizer for Programmers

A flowchart is a visual representation of the sequence of steps in a program. It helps programmers plan and organize the logic of their program.

Example: Using RAPTOR, a flowcharting tool, to design an authentication system for logging into an account.

Use Cases:

• Designing a traffic light control system logic.
• Mapping the steps in an online order process.

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Pseudocode

Definition: Pseudocode is a simplified, language-independent way of outlining a program’s logic before actual coding.

Example:

IF user enters correct password

    THEN grant access

ELSE

    Deny access

Use Cases:

• Drafting the logic for ATM transactions.
• Sketching the steps in a self-driving car’s decision-making process.

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Categories of Programming Languages

1. Assembly Language

Definition: A low-level programming language that interacts directly with hardware.

Example:

• Writing firmware for embedded systems like washing machines and microcontrollers.

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2. Compiled Programming Languages

Definition: High-level languages that require compilation into machine code before execution.

Examples: C++, C#, Java, COBOL, Pascal, Fortran, BASIC

Use Cases:

• C++ for game engines like Unreal Engine.
• Java for Android mobile applications.
• C# for Windows desktop applications.

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3. Interpreted Programming Languages

Definition: Languages that execute code line-by-line at runtime without requiring compilation.

Examples: Python, JavaScript, Perl

Use Cases:

• JavaScript for dynamic websites.
• Python for AI and data analysis.
• Perl for text processing in UNIX.

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Types of Interpreted Languages

• Scripting languages: Used for automating tasks (e.g., PowerShell, Linux Shell scripting).
• Scripted languages: Require an interpreter (e.g., JavaScript running in a browser).
• Markup languages: Used for text formatting and web design (e.g., HTML, XML).

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Differences Between Compiled and Interpreted Languages

Task	Compiled	Interpreted
Translation	Entire program at once	Line-by-line execution
Execution Speed	Faster	Slower
Debugging	Harder	Easier
Example	C++	Python

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Query Languages

Definition: Languages used to retrieve and manipulate data from databases.

Example:

• SQL (Structured Query Language)

Use Case:

• Fetching customer purchase records from an e-commerce database.

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Object-Oriented Programming (OOP)

Definition: A programming paradigm based on objects containing identity, state, and behavior.

Examples: Java, C++, C#, Python, PHP, Ruby

Use Cases:

• Java for large-scale enterprise applications.
• Python for AI-based recommendation systems.
• C++ for game development.

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Programming Concepts

Identifiers

Definition: Names used to identify program elements like variables and functions.

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Variables

Definition: Stores a value that may change during execution.

Example:

age = 25

Use Case: Storing a user’s age in a profile.

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Constants

Definition: Stores a value that cannot change.

Example:

#define PI 3.14159

Use Case: Using PI in a circle area calculation.

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Containers

Definition: Store multiple values.

• Arrays (fixed size, same type)
• Vectors (dynamic size, mixed types)

Use Cases:

• Storing a list of student grades.
• Managing inventory stock in a warehouse.

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Functions and Procedures

Functions

Reusable code that returns a value.

Example:

def add(x, y):

    return x + y

Use Case: Performing mathematical calculations in an accounting system.

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Procedures

Reusable code that does not return a value.

Use Case: Sending email notifications after user registration.

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Objects

Definition: A collection of attributes (properties) and methods.

Example:

class Car:

    def __init__(self, brand, model):

        self.brand = brand

        self.model = model

Use Case: Modeling real-world cars in a simulation.

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Branching and Loops

Branching

Definition: Controls the program flow using if-else statements.

Example:

if score >= 50:

    print(“Pass”)

else:

    print(“Fail”)

Use Case: Determining if a student passes or fails an exam.

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Loops

Definition: Repeats a task until a condition is met.

Example:

for i in range(5):

    print(i)

Use Case: Displaying numbers from 0 to 4.

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Operators

Comparison Operators:

• == (Equal to)
• != (Not equal to)
• <, >, <=, >= (Comparison)

Logical Operators:

• AND – Both conditions must be TRUE.
• OR – At least one condition must be TRUE.
• XOR – Only one condition must be TRUE.

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Common Data Types

Data Type	Description	Example
Char	Single character	‘A’
String	Text	“Hello”
Integer	Whole number	10
Float	Decimal number	3.14
Boolean	True/False	True