Object-Oriented Programming Using C++ Language with File Handling, Exception Handling, and Standard Template Library

 

Introduction

C++ is one of the most powerful programming languages, known for its speed, versatility, and object-oriented capabilities. In 2025, despite the rise of Python, Java, and other languages, C++ still holds a strong place in system programming, game development, competitive programming, and real-time applications.

This article will help you understand Object-Oriented Programming (OOP) in C++ along with file handling, exception handling, and the Standard Template Library (STL).

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What is Object-Oriented Programming (OOP)?

OOP is a programming paradigm that structures code around objects instead of functions.

Benefits of OOP in C++:

• Better organization of code

• Reusability with inheritance

• Easier debugging and maintenance

• Closer representation of real-world problems

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Core Principles of OOP in C++

1. Encapsulation: Wrapping data and methods into a single unit (class).

2. Inheritance: Deriving new classes from existing ones.

3. Polymorphism: Ability of one function to act differently depending on context.

4. Abstraction: Hiding implementation details and exposing only functionality.

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C++ Classes and Objects

A class is a blueprint, while an object is an instance of the class.

class Student {
  public:
    string name;
    int age;
    
    void display() {
      cout << "Name: " << name << ", Age: " << age;
    }
};

int main() {
  Student s1;
  s1.name = "John";
  s1.age = 21;
  s1.display();
  return 0;
}

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Constructors and Destructors

• Constructors initialize objects automatically.

• Destructors clean up memory when objects go out of scope.

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Function & Operator Overloading

• Function Overloading: Same function name, different parameters.

• Operator Overloading: Redefine operators like + for custom objects.

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Inheritance in C++

Inheritance allows reusing code.

Types:

• Single

• Multiple

• Multilevel

• Virtual (to avoid ambiguity in multiple inheritance)

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Polymorphism in C++

• Compile-time polymorphism: Function overloading & operator overloading.

• Runtime polymorphism: Achieved using virtual functions.

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Abstraction in C++

Achieved using abstract classes and pure virtual functions.

class Shape {
  public:
    virtual void draw() = 0; // Pure virtual function
};

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File Handling in C++

C++ provides fstream for file handling.

#include <fstream>
ofstream file("data.txt");
file << "Hello World";
file.close();

• ifstream → Read from files

• ofstream → Write to files

• fstream → Both read and write

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Exception Handling in C++

C++ uses try, catch, and throw for error management.

try {
   int a = 10, b = 0;
   if(b == 0) throw "Division by zero!";
   cout << a/b;
}
catch(const char* msg) {
   cout << "Error: " << msg;
}

This prevents program crashes and improves reliability.

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Introduction to STL

The Standard Template Library (STL) provides predefined classes and functions to save time.

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Components of STL

1. Containers: Store data (vector, list, map, set)

2. Algorithms: Ready-made functions (sort, find, count)

3. Iterators: Bridge between containers and algorithms

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Combining OOP with STL

Example: Using vector in a class to store records.

class Student {
  public:
    string name;
    int marks;
};

vector<Student> students;

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Practical Applications

• Banking System → Manage accounts using classes, exception handling for invalid inputs.

• Student Record System → Store data with file handling + STL containers.

• Billing System → Handle unexpected errors with exception handling.

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Conclusion

C++ remains a powerful and relevant language in 2025 because of its object-oriented design, efficient file handling, strong exception management, and versatile STL. Mastering these concepts will make you a better programmer and prepare you for real-world applications in IT and software development.

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FAQs

1. Why should I learn C++ when other languages exist?
C++ is fast, powerful, and widely used in performance-critical applications like gaming and operating systems.

2. Is STL mandatory for learning OOP?
Not mandatory, but it saves time and makes coding easier.

3. How is exception handling useful in real projects?
It prevents crashes, ensuring reliability in software.

4. Can file handling be integrated with STL?
Yes, STL containers can store and process file data efficiently.

5. Is C++ still relevant in 2025?
Absolutely! C++ remains essential in gaming, system software, embedded systems, and competitive programming.