Design Patterns in C++

A collection of Design Pattern and SOLID Principle examples implemented in C++.

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📂 Project Structure

DesignPatterns/
├── BehavioralDesignPattern/
│   ├── Observer.md
│   └── ObserverDesignPattern.cpp
├── CreationalDesign/
│   ├── Builder Design Pattern/
│   │   ├── BuilderDesignPattern.cpp
│   │   ├── BuilderDesignPattern.md
│   │   ├── HTTPRequestBuilder.cpp
│   │   └── HTTPRequestBuilder.md
│   ├── Factory/
│   │   ├── FactoryDesignPattern.cpp
│   │   └── FactoryDesignPattern.md
│   └── SingletonDesign Pattern/
│       ├── DatabaseExample.cpp
│       ├── Logger.cpp
│       └── singletondesignPattern.md
├── ObjectOrientedProgramming/
│   ├── abstraction.cpp
│   ├── Encapsulation.cpp
│   ├── Inheritance/
│   │   ├── MultilevelInheritance.cpp
│   │   ├── MultilevelInheritance.md
│   │   ├── MultipleInheritance.cpp
│   │   ├── MultipleInheritance.md
│   │   ├── SingleInheritance.cpp
│   │   └── SingleInheritance.md
│   └── Polymorphism/
│       ├── Polymorphism.md
│       ├── compile/
│       │   ├── CompileTimePolymorphism.cpp
│       │   └── CompileTimePolymorphism.md
│       └── runtime/
│           ├── RuntimePolymorphism.cpp
│           └── RuntimePolymorphism.md
└── Solid/
    ├── SingleResponsibilityPrinciple.md
    ├── singleResponsibilityPrinciple.cpp
    ├── OpenClosedPrinciple.md
    ├── OpenClosedPrinciple.cpp
    ├── LiskovSubstitutionPrinciple.md
    ├── LiskovSubstitutionPrinciple.cpp
    ├── InterfaceSegregationPrinciple.md
    ├── InterfaceSegregationPrinciple.cpp
    ├── DependencyInversionPrinciple.md
    └── DependencyInversionPrinciple.cpp

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SOLID Principles

Each principle has a theory doc (.md) and a C++ implementation (.cpp) showing both a violation and the correct approach.

#	Principle	Theory	Code
S	Single Responsibility Principle	SRP Theory	SRP Code
O	Open/Closed Principle	OCP Theory	OCP Code
L	Liskov Substitution Principle	LSP Theory	LSP Code
I	Interface Segregation Principle	ISP Theory	ISP Code
D	Dependency Inversion Principle	DIP Theory	DIP Code

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Creational Design Patterns

Pattern	Example	Code	Documentation
Builder	Step-by-step object construction	BuilderDesignPattern.cpp	Theory
Builder	HTTP Request construction	HTTPRequestBuilder.cpp	HTTP Example
Factory	Object creation through factory method	FactoryDesignPattern.cpp	Theory
Singleton	Database connection	DatabaseExample.cpp	Theory
Singleton	Logger instance	Logger.cpp	Theory

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Object-Oriented Programming Basics

Topic	Example	Documentation
Inheritance	SingleInheritance.cpp	Theory
Inheritance	MultilevelInheritance.cpp	Theory
Inheritance	MultipleInheritance.cpp	Theory
Polymorphism	CompileTimePolymorphism.cpp	Theory
Polymorphism	RuntimePolymorphism.cpp	Theory

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How to Run

SOLID Principles (C++17+)

Compile with C++17 or later:

g++ -std=c++17 -o output Solid/OpenClosedPrinciple.cpp
./output

Creational Design Patterns (C++20)

All creational patterns use C++20 features (primarily std::format):

# Builder Pattern - Computer Configuration
g++ -std=c++20 -o builder CreationalDesign/Builder\ Design\ Pattern/BuilderDesignPattern.cpp
./builder

# Builder Pattern - HTTP Request Construction
g++ -std=c++20 -o http_request CreationalDesign/Builder\ Design\ Pattern/HTTPRequestBuilder.cpp
./http_request

# Singleton - Database Example
g++ -std=c++20 -o database CreationalDesign/SingletonDesign\ Pattern/DatabaseExample.cpp
./database

# Singleton - Logger Example
g++ -std=c++20 -o logger CreationalDesign/SingletonDesign\ Pattern/Logger.cpp
./logger

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License

This project is for educational purposes.