Programming Concepts & OOP - Complete Guide

Last Updated: August 19, 2026 | Marks Weightage: ~15 Marks | BPSC CS Teacher

Master Programming Concepts and Object-Oriented Programming with this comprehensive guide for the BPSC Computer Science Teacher exam.

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1. Problem Solving - Algorithms & Flowcharts

📝 Algorithm

Step-by-step procedure to solve a problem

Input → Process → Output
Example: Algorithm to add two numbers

📊 Flowchart

Visual representation of an algorithm

Oval: Start/End
Rectangle: Process
Diamond: Decision
Parallelogram: Input/Output

💡 Exam Tip: Practice writing algorithms and drawing flowcharts for simple problems like finding the maximum of three numbers.

2. Data Types & Variables

📊 Primitive

int (integer)
float (decimal)
char (character)
bool (boolean)

📊 Derived

Array
Pointer
Structure
Union

📊 User-defined

Class
Enum
Typedef

📌 Variables: Named memory locations. Must be declared before use. Example: int age = 25;

3. Control Structures

⚡ Decision Making

if: if (condition) { }
if-else: if (condition) { } else { }
switch: switch(variable) { case: }
Ternary: condition ? true : false

🔄 Loops

for: for(init; condition; increment) { }
while: while(condition) { }
do-while: do { } while(condition);
break: Exit loop
continue: Skip iteration

4. Functions

Definition: return_type function_name(parameters) { body }
Call by Value: Passes copy of data
Call by Reference: Passes address (modifies original)
Recursion: Function calls itself

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

5. Arrays & Strings

📊 Arrays

1D: int arr[5] = {1,2,3,4,5};
2D: int arr[3][4]; (3 rows, 4 columns)
Indexing: Starts from 0

📝 Strings

C: char str[] = "Hello"; (Null-terminated)
C++: string str = "Hello"; (STL string)
String functions: strlen(), strcpy(), strcat()

6. Pointers

Pointer: Variable that stores memory address

Declaration: int *ptr;
Address of: &var
Dereference: *ptr (value at address)
NULL Pointer: int *ptr = NULL;

💡 Exam Tip: Pointers are heavily tested in C/C++ programming questions.

7. Object-Oriented Programming (OOP) Principles

🔒 Encapsulation

Hiding internal details. Data is private, accessed via public methods.

🔄 Inheritance

Creating new classes from existing ones. Code reusability.

🎯 Polymorphism

Many forms. Function overloading, operator overloading, virtual functions.

📐 Abstraction

Showing only essential features. Abstract classes and interfaces.

8. Classes & Objects

🏷️ Class

class Student {
private:
    string name;
    int rollNo;
public:
    // Constructor
    Student(string n, int r) { name = n; rollNo = r; }
    // Method
    void display() { cout << name << " " << rollNo; }
};

🏷️ Object

Student s1("John", 101); // Object created
s1.display(); // Calling method

📌 Constructors & Destructors: Constructor initializes object, Destructor cleans up.

9. Exception Handling

Handling runtime errors gracefully.

try: Contains code that might throw exception
catch: Handles the exception
throw: Throws an exception

Example:

try {
    int age = -5;
    if (age < 0) throw "Invalid age!";
}
catch (const char* msg) {
    cout << msg;
}

10. Frequently Asked Questions

❓ What is the difference between Call by Value and Call by Reference?

Call by Value passes a copy; Call by Reference passes the actual address, allowing modifications.

❓ What are the 4 pillars of OOP?

Encapsulation, Inheritance, Polymorphism, Abstraction

❓ What is the difference between an Array and a Linked List?

Array has fixed size, contiguous memory. Linked List is dynamic, non-contiguous.

❓ What is a Constructor?

A special method called when an object is created. It initializes the object.

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