System Design & C++ Interview Preparation

A comprehensive resource for mastering System Design, Object-Oriented Programming (OOP), and C++ fundamentals for technical interviews.

🎯 Purpose

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

📚 What's Inside

Current Topics

1. Access Modifiers

Complete guide to C++ access control mechanisms.

Covers:

• public, protected, private access 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 & visibility
• example2/ - Protected "through what?" rule
• example3/ - Real-world: Bank account system
• example4/ - Inheritance types (public/protected/private)

📖 Read the full guide →

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2. Constructors & Destructors

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 fundamentals
• 02_parameterized_constructor.cpp - Controlled object creation
• 03_copy_constructor.cpp - Shallow vs Deep copy explained
• 04_constructor_overloading.cpp - Function overloading with 4 examples
• 05_initialization_list.cpp - Performance optimization
• 06_destructor_basics.cpp - Resource cleanup & RAII
• 07_constructor_destructor_order.cpp - Inheritance order & virtual destructors
• 08_special_cases.cpp - Explicit, Singleton, Factory patterns
• explicit_explained.cpp - explicit keyword deep dive
• cnstrs.cpp - Working example with Rule of Three

Status: Parts 1-8 complete ✅ CORE TOPICS DONE!

📖 Read the full guide →

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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 concepts
• 02_types_of_inheritance.cpp - All inheritance types
• 03_access_control.cpp - Access specifier rules
• 04_constructor_destructor_order.cpp - Object lifecycle
• 05_function_overriding.cpp - Method overriding
• 06_virtual_functions.cpp - Polymorphism basics
• 07_abstract_classes.cpp - Pure virtual functions
• 08_multiple_inheritance.cpp - Multiple base classes
• 09_real_world_example.cpp - GUI toolkit demo
• 10_private_inheritance_example.cpp - Advanced patterns
• vptr_vtable_visual.cpp - Internal mechanism visualization
• diamondprob.cpp - Diamond problem solution

Status: All 10 parts complete ✅ FULLY DOCUMENTED!

📖 Read the full guide →

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4. Concurrency Fundamentals

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 12 Files:

• 00_single_thread_basics.cpp - Single thread timing demo
• 00_multi_thread_basics.cpp - Work splitting with atomic
• 01_process_vs_thread.cpp - fork vs thread comparison
• 02_ipc_internals.cpp - IPC mechanisms demo
• 02_ipc_pipe_basics.cpp - Pipe-based IPC basics
• 03_process_internals_deep_dive.md - TCB/PCB kernel details
• 04_thread_memory_layout.cpp - Stack/heap/TLS addresses
• 05_thread_vs_process_memory.md - Memory layout comparison
• 06_thread_create_basics.cpp - Simple thread syntax
• 07_process_create_basics.cpp - fork/exec/wait basics
• process_exp.cpp - Process creation experiment
• thread_experiments.cpp - Threading experiments playground

Status: Complete ✅ Systems perspective!

📖 Read the full guide →

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5. OOP Relationships

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.

📖 Read the full guide →

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6. Templates & Generics

Intro to writing reusable, type-safe code with templates.

Covers (so far):

• What templates are and why they matter (generic, type-safe reuse)
• Basic syntax for function and class templates

Includes 2 Examples:

• genrics_basic.cpp — function template addnum, class template Box<T>
• concepts_vs_sfinae.cpp — SFINAE constraints (C++17 compilable) with C++20 concepts documented as theory

📖 Read the guide → | ▶️ cd generics && make FILE=genrics_basic.cpp run

Next Up: constraints (concepts), specialization, perfect forwarding/move-aware templates

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7. Exception Handling

Practical exception-safety patterns with working samples.

Covers:

• try/catch basics and throwing functions
• Standard exception hierarchy and custom exceptions
• RAII stack unwinding
• Exception safety guarantees and noexcept
• Futures, nested exceptions, and error codes

Includes:

• 01_try_catch_basics.cpp through 10_error_code_vs_exception.cpp
• experiments.cpp - sandbox for patterns

📖 Read the guide →

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8. Synchronization

Thread-safety primitives and patterns.

Covers:

• Mutexes and shared mutexes
• Semaphores (native and C++20)
• Classic producer-consumer patterns
• Traffic counter example

Includes:

• sync_mutex.cpp, sync_shared_mutex.cpp
• semaphore_native.cpp, semaphore_cpp20.cpp
• producer_consumer.cpp, producer_consumer_advanced.cpp
• traffic_counter.cpp

📖 Read the guide →

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🏗️ Projects

Project suites demonstrating different C++ concepts and design patterns.

📖 View All Projects →

Quick Overview:

Project	Focus	Tech	Score
HMS	All 4 OOP Relationships	Raw Pointers	9/10
Payment Service	Polymorphism & RAII	Smart Pointers	9.5/10
System Programming (WIP)	Unix process/thread exercises	C/C++	WIP

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 →

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🗂️ Repository Structure

systemdesign/
├── README.md
├── acessmodifiers/
│   ├── README.md
│   ├── example1/
│   ├── example2/
│   ├── example3/
│   └── example4/
├── association/
│   ├── README.md
│   ├── PROBLEM_STATEMENT.md
│   ├── 01_association_basics.cpp ... 06_complete_example.cpp
│   ├── hms.cpp
│   └── makefile
├── concurrency/
│   ├── README.md
│   ├── 00_single_thread_basics.cpp ... 07_process_create_basics.cpp
│   ├── 02_ipc_pipe_basics.cpp
│   ├── process_exp.cpp
│   ├── thread_experiments.cpp
│   └── makefile
├── constructors-destructors/
│   ├── README.md
│   ├── 01_basic_constructor.cpp ... 08_special_cases.cpp
│   ├── explicit_explained.cpp
│   └── cnstrs.cpp
├── exceptionalhandling/
│   ├── README.md
│   ├── 01_try_catch_basics.cpp ... 10_error_code_vs_exception.cpp
│   ├── experiments.cpp
│   └── makefile
├── functorsExecutioners/
│   ├── README.md
│   ├── fp.cpp
│   ├── lambda_explanation.cpp
│   ├── lambda_explanation.md
│   └── makefile
├── generics/
│   ├── README.md
│   ├── genrics_basic.cpp
│   ├── concepts_vs_sfinae.cpp
│   └── makefile
├── inheritance/
│   ├── README.md
│   ├── 01_inheritance_basics.cpp ... 10_private_inheritance_example.cpp
│   ├── vptr_vtable_visual.cpp
│   └── diamondprob.cpp
├── projects/
│   ├── README.md
│   ├── HMS/
│   ├── paymentsystem/
│   └── systemprogramming/
└── synchronization/
    ├── README.md
    ├── sync_mutex.cpp, sync_shared_mutex.cpp
    ├── semaphore_native.cpp, semaphore_cpp20.cpp
    ├── producer_consumer.cpp, producer_consumer_advanced.cpp
    └── traffic_counter.cpp

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 for a full index and lambda_explanation.md for detailed lambda explanations and examples.

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🚀 Getting Started

Prerequisites

• C++ compiler (g++, clang++)
• Basic understanding of C++ syntax
• Terminal/command line familiarity

Running Examples

Each topic directory contains runnable examples:

# Navigate to a topic
cd acessmodifiers/example1

# Compile
g++ -o am.out am.cpp

# Run
./am.out

# Or for constructors
cd constructors-destructors
g++ -o basic.out 01_basic_constructor.cpp
./basic.out

Refer to individual README files for specific compilation instructions.

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📖 Learning Path

For Interview Prep:

1. Start with fundamentals: Access modifiers, encapsulation
2. Move to OOP concepts: Inheritance, polymorphism, abstraction
3. Study design patterns: Singleton, Factory, Observer, etc.
4. Practice system design: Design real-world systems

Recommended Order:

• ✅ 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 (basics added)
• 🔜 RAII & Smart Pointers
• 🔜 Move Semantics & Perfect Forwarding
• 🔜 Design Patterns
• 🔜 Exception Handling
• 🔜 System Design Case Studies

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🎓 How to Use This Repo

For Self-Study:

1. Read the topic's README for theory
2. Study the code examples
3. Compile and run the examples yourself
4. Modify the code to test your understanding
5. Practice the interview questions

For Interview Prep:

1. Review the "Common Interview Questions" sections
2. Understand the "why" behind each concept
3. Practice explaining concepts out loud
4. Code examples from memory
5. Focus on real-world applications

For Contributors:

• Each topic should have a comprehensive README
• Include working, compilable examples
• Add interview questions with answers
• Provide real-world use cases

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🤝 Contributing

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

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📝 Topics Roadmap

✅ Completed

• 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)
• Exception Handling (safety levels, noexcept, futures, error codes)
• Synchronization Primitives (mutexes, semaphores, producer-consumer)

🚧 In Progress

• Templates & Generics (basics done; concepts/specialization next)
• RAII & Smart Pointers
• System Programming project enhancements

📋 Planned

• Move Semantics & Perfect Forwarding
• STL Containers & Algorithms
• Design Patterns (Gang of Four)
• Memory Management
• Concurrency & Threading
• System Design Case Studies

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💡 Interview Tips

Key Principles to Remember:

1. Understand the "why": Don't just memorize—understand the reasoning
2. Practice explaining: Can you explain it to someone else?
3. Code without IDE: Practice writing code by hand or in simple editors
4. Think about trade-offs: Every design decision has pros and cons
5. 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

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📬 Feedback & Questions

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

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⚠️ Disclaimer

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. 🚀

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📜 License

This is an educational resource. Feel free to use, modify, and share for learning purposes.

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Happy Learning! 🚀

Last Updated: December 30, 2025 Topics will be added gradually as we progress through interview preparation.