A comprehensive resource for mastering System Design, Object-Oriented Programming (OOP), and C++ fundamentals for technical interviews.
This repository is designed for:
- Interview preparation: Brush up on core concepts before technical rounds
- Learning system design: Step-by-step exploration of OOP principles
- Hands-on practice: Working code examples with detailed explanations
- Community resource: Anyone interested in strengthening their C++ and system design knowledge
Complete guide to C++ access control mechanisms.
Covers:
public,protected,privateaccess specifiers- Access vs Visibility (compilation phases)
- Friend mechanism (not an access specifier!)
- Protected access rules ("through what object?")
- Inheritance and access control
- Real-world examples and interview questions
Includes 4 Working Examples:
example1/- Basic access control & visibilityexample2/- Protected "through what?" ruleexample3/- Real-world: Bank account systemexample4/- Inheritance types (public/protected/private)
Deep dive into object lifecycle management in C++.
Covers:
- Default, Parameterized, and Copy Constructors
- Shallow vs Deep Copy (critical for interviews!)
- Constructor Overloading
- Initialization Lists
- Destructors and RAII
- Rule of Three/Five
- Memory management with dynamic allocation
- Constructor calling rules and delegation
Includes Comprehensive Examples:
01_basic_constructor.cpp- Constructor fundamentals02_parameterized_constructor.cpp- Controlled object creation03_copy_constructor.cpp- Shallow vs Deep copy explained04_constructor_overloading.cpp- Function overloading with 4 examples05_initialization_list.cpp- Performance optimization06_destructor_basics.cpp- Resource cleanup & RAII07_constructor_destructor_order.cpp- Inheritance order & virtual destructors08_special_cases.cpp- Explicit, Singleton, Factory patternscnstrs.cpp- Working example with Rule of Three
Status: Parts 1-8 complete ✅ CORE TOPICS DONE!
3. Inheritance
Complete guide to class hierarchies, polymorphism, and runtime dispatch in C++.
Covers:
- Inheritance basics (IS-A relationship)
- Types of inheritance (Single, Multiple, Multilevel, Hierarchical, Hybrid)
- Access control in inheritance (public, protected, private)
- Constructor/Destructor order in inheritance
- Function overriding and virtual functions
- Polymorphism and dynamic dispatch
- Abstract classes and pure virtual functions
- Diamond problem and virtual inheritance
- vptr/vtable mechanism deep dive (system-level understanding)
- Real-world examples (GUI toolkit, device drivers)
- Interview questions and best practices
Includes 10 Complete Examples:
01_inheritance_basics.cpp- Fundamental concepts02_types_of_inheritance.cpp- All inheritance types03_access_control.cpp- Access specifier rules04_constructor_destructor_order.cpp- Object lifecycle05_function_overriding.cpp- Method overriding06_virtual_functions.cpp- Polymorphism basics07_abstract_classes.cpp- Pure virtual functions08_multiple_inheritance.cpp- Multiple base classes09_real_world_example.cpp- GUI toolkit demo10_private_inheritance_example.cpp- Advanced patternsvptr_vtable_visual.cpp- Internal mechanism visualizationdiamondprob.cpp- Diamond problem solution
Status: All 10 parts complete ✅ FULLY DOCUMENTED!
Systems programming perspective on processes, threads, and memory management.
Covers:
- Process vs Thread (fundamental differences)
- IPC mechanisms (pipes, shared memory, signals)
- Memory layouts (stack, heap, TLS, code/data segments)
- TCB/PCB in kernel memory
- Thread creation basics (pthread, std::thread)
- Process creation (fork, exec, wait)
- Virtual memory and address translation
- Context switching internals
Includes 9 Files:
00_single_thread_basics.cpp- Single thread timing demo00_multi_thread_basics.cpp- Work splitting with atomic01_process_vs_thread.cpp- fork vs thread comparison02_ipc_internals.cpp- IPC mechanisms demo03_process_internals_deep_dive.md- TCB/PCB kernel details04_thread_memory_layout.cpp- Stack/heap/TLS addresses05_thread_vs_process_memory.md- Memory layout comparison06_thread_create_basics.cpp- Simple thread syntax07_process_create_basics.cpp- fork/exec/wait basics
Status: Complete ✅ Systems perspective!
Demonstrating all 4 OOP relationships with real-world Hospital Management System.
Covers:
- Inheritance (IS-A): Doctor/Patient inherit from Person
- Composition (Dies Together): Address in Person, MedicalRecord in Patient
- Aggregation (Independent): Department has Doctors
- Association (Temporary): Doctor examines Patient
- UML diagrams and arrow directions
- Memory management with raw pointers (pre-RAII)
- Interview-ready implementation
Project:
hms.cpp- Complete Hospital Management System- Person base class with Address composition
- Doctor and Patient inheritance
- Department aggregation using pointers
- examine() method for association
- All 4 relationships demonstrated
Status: Complete ✅ Interview ready! Score: 9/10
Note: Using raw pointers for learning; will upgrade to smart_ptr after RAII topic.
2 Complete Interview Projects demonstrating different C++ concepts and design patterns.
| Project | Focus | Tech | Score |
|---|---|---|---|
| HMS | All 4 OOP Relationships | Raw Pointers | 9/10 |
| Payment Service | Polymorphism & RAII | Smart Pointers | 9.5/10 |
Key Highlights:
- ✅ Interview-ready implementations with comprehensive documentation
- ✅ UML diagrams and design explanations
- ✅ Practice questions and talking points included
- ✅ No compiler warnings, clean code quality
- ✅ Makefile for easy compilation
📖 Explore Projects → | See Comparison Table →
systemdesign/ ├── README.md # This file ├── acessmodifiers/ # Access modifiers topic │ ├── README.md # Comprehensive guide │ ├── example1/ # Basic examples │ ├── example2/ # Protected rules │ ├── example3/ # Real-world scenarios │ └── example4/ # Inheritance types ├── constructors-destructors/ # Constructors & Destructors │ ├── README.md # Complete roadmap │ ├── 01_basic_constructor.cpp │ ├── 02_parameterized_constructor.cpp │ ├── 03_copy_constructor.cpp │ ├── 04_constructor_overloading.cpp │ ├── 05_initialization_list.cpp │ ├── 06_destructor_basics.cpp │ ├── 07_constructor_destructor_order.cpp │ ├── 08_special_cases.cpp │ └── cnstrs.cpp # Working example ├── inheritance/ # Inheritance & Polymorphism │ ├── README.md # Complete roadmap with navigation │ ├── 01_inheritance_basics.cpp │ ├── 02_types_of_inheritance.cpp │ ├── 03_access_control.cpp │ ├── 04_constructor_destructor_order.cpp │ ├── 05_function_overriding.cpp │ ├── 06_virtual_functions.cpp │ ├── 07_abstract_classes.cpp │ ├── 08_multiple_inheritance.cpp │ ├── 09_real_world_example.cpp │ ├── 10_private_inheritance_example.cpp │ ├── vptr_vtable_visual.cpp │ └── diamondprob.cpp ├── concurrency/ # Concurrency Fundamentals │ ├── README.md # Systems programming perspective │ ├── 00_single_thread_basics.cpp │ ├── 00_multi_thread_basics.cpp │ ├── 01_process_vs_thread.cpp │ ├── 02_ipc_internals.cpp │ ├── 03_process_internals_deep_dive.md │ ├── 04_thread_memory_layout.cpp │ ├── 05_thread_vs_process_memory.md │ ├── 06_thread_create_basics.cpp │ ├── 07_process_create_basics.cpp │ └── makefile ├── association/ # OOP Relationships │ ├── README.md # All 4 OOP relationships guide │ ├── hms.cpp # Hospital Management System (Interview Project) │ ├── HMS.png # UML diagram │ └── makefile ├── functorsExecutioners/ # Function pointers, functors, lambdas │ ├── README.md # Index for function pointer & lambda topics │ ├── fp.cpp # Function pointer examples │ ├── lambda_explanation.cpp # Lambda examples │ └── lambda_explanation.md # Lambda explanations & guide ├── projects/ # Interview Projects │ └── paymentsystem/ # Payment Service System │ ├── README.md # Complete documentation │ ├── payment_system.cpp # Polymorphism & RAII demo │ └── makefile ├── ProductService/ # Java Spring Boot project (for practice) └── backendproject/ # Other practice projects
### Function Pointers, Functors, and Lambdas
Explore modern C++ callable objects, including:
- Function pointers (basic, callback, arrays, strategy)
- Lambdas (syntax, captures, STL, threading, generic, etc.)
See [`functorsExecutioners/README.md`](./functorsExecutioners/README.md) for a full index and [`lambda_explanation.md`](./functorsExecutioners/lambda_explanation.md) for detailed lambda explanations and examples.
---
## 🚀 Getting Started
### Prerequisites
- C++ compiler (g++, clang++)
- Basic understanding of C++ syntax
- Terminal/command line familiarity
### Running Examples
Each topic directory contains runnable examples:
```bash
# Navigate to a topic
cd acessmodifiers/example1
# Compile
g++ -o am.out am.cpp
# Run
./am.out
# Or for constructors
cd constructors
g++ -o basic.out 01_basic_constructor.cpp
./basic.out
Refer to individual README files for specific compilation instructions.
- Start with fundamentals: Access modifiers, encapsulation
- Move to OOP concepts: Inheritance, polymorphism, abstraction
- Study design patterns: Singleton, Factory, Observer, etc.
- Practice system design: Design real-world systems
- ✅ Access Modifiers (Complete)
- ✅ Constructors & Destructors (Complete - All 8 parts done!)
- ✅ Inheritance & Polymorphism (Complete - All 10 parts done!)
- ✅ Concurrency Fundamentals (Complete - Systems perspective!)
- ✅ OOP Relationships (Complete - HMS project!)
- 🔜 Templates & Generic Programming
- 🔜 RAII & Smart Pointers
- 🔜 Move Semantics & Perfect Forwarding
- 🔜 Design Patterns
- 🔜 Exception Handling
- 🔜 System Design Case Studies
- Read the topic's README for theory
- Study the code examples
- Compile and run the examples yourself
- Modify the code to test your understanding
- Practice the interview questions
- Review the "Common Interview Questions" sections
- Understand the "why" behind each concept
- Practice explaining concepts out loud
- Code examples from memory
- Focus on real-world applications
- Each topic should have a comprehensive README
- Include working, compilable examples
- Add interview questions with answers
- Provide real-world use cases
This is a living resource that will grow over time. Topics will be added gradually based on interview relevance and community needs.
Contribution Guidelines:
- Keep explanations clear and concise
- Include working code examples
- Add compilation instructions
- Cover common interview gotchas
- Reference real-world scenarios
- Access Modifiers (public, protected, private, friend)
- Constructors & Destructors (All 8 parts)
- Inheritance & Polymorphism (All 10 parts + vptr/vtable deep dive)
- Concurrency Fundamentals (Processes, Threads, IPC, Memory Layouts)
- OOP Relationships (Inheritance, Composition, Aggregation, Association)
- Project: Hospital Management System (HMS)
- RAII & Smart Pointers
- RAII & Resource Management
- Smart Pointers (unique_ptr, shared_ptr, weak_ptr)
- Move Semantics & Perfect Forwarding
- STL Containers & Algorithms
- Design Patterns (Gang of Four)
- Exception Handling
- Memory Management
- Concurrency & Threading
- System Design Case Studies
Key Principles to Remember:
- Understand the "why": Don't just memorize—understand the reasoning
- Practice explaining: Can you explain it to someone else?
- Code without IDE: Practice writing code by hand or in simple editors
- Think about trade-offs: Every design decision has pros and cons
- Real-world context: Connect concepts to actual software problems
During Interviews:
- Clarify requirements before coding
- Think out loud—show your thought process
- Start with a simple solution, then optimize
- Discuss edge cases and error handling
- Know the time/space complexity
- ProductService/: Java Spring Boot service (for backend practice)
- backendproject/: Additional backend examples
This repository is designed to help developers prepare for technical interviews. If you find it helpful, consider:
- ⭐ Starring the repo
- 🐛 Reporting issues or unclear explanations
- 💡 Suggesting new topics
- 🤝 Contributing examples or improvements
This is a learning resource created for educational purposes.
- 📖 Learning in Progress: Content is created as part of ongoing interview preparation and learning
- 🐛 Corrections Welcome: If you find any errors, inaccuracies, or better explanations, please feel free to:
- Open an issue
- Submit a pull request
- Start a discussion
- 🤝 Community Driven: This repository benefits from collective knowledge—your corrections help everyone learn
- 🎓 Educational Intent: All content is meant for learning and skill development
- 📚 No Guarantees: While we strive for accuracy, always cross-reference with official documentation and authoritative sources
We're all learning together! If something doesn't seem right, it probably needs correction. Don't hesitate to point it out—that's how we all improve. 🚀
This is an educational resource. Feel free to use, modify, and share for learning purposes.
Happy Learning! 🚀
Last Updated: November 16, 2025 Topics will be added gradually as we progress through interview preparation.