docs(10_Wiki): 위키 구조 정리 — 언어 튜토리얼 카테고리 폴더 제거 + 신규 자산 동기화

Topic_CSS/Topic_HTML/Topic_JavaScript/Topic_Prompt/Topic_Comfyui 등 기존 카테고리 폴더를 정리하고, Topic_Graphic/Dev 등 신규 산출물과 Topics 내부 세션/메모리 기록을 동기화.
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+---
+id: csharp-abstract
+title: "C# Abstraction"
+category: "Programming_Language"
+status: "draft"
+verification_status: "conceptual"
+canonical_id: ""
+aliases: ["abstract class method C#", "C# 추상화"]
+duplicate_of: ""
+source_trust_level: "B"
+confidence_score: 0.85
+created_at: 2026-07-04
+updated_at: 2026-07-04
+review_reason: ""
+merge_history: []
+tags: ["csharp", "programming-language", "w3schools", "oop", "abstraction"]
+raw_sources: ["https://www.w3schools.com/cs/cs_abstract.php"]
+applied_in: []
+github_commit: ""
+---
+
+# [[CSharp Abstraction]]
+
+## 🎯 한 줄 통찰 (One-line insight)
+Where C++ makes a class abstract IMPLICITLY (simply by containing at least one pure virtual function written as `virtual void f() = 0;`, with no dedicated "this class is abstract" keyword), C# makes it EXPLICIT with a dedicated `abstract` keyword on both the class AND each bodyless method (`abstract class Animal { public abstract void animalSound(); }`) — the same underlying restriction (cannot instantiate, must be inherited to be used, subclass MUST supply the missing method body) is enforced, but C# spells out the intent in the declaration itself rather than deriving it as a side-effect of the method's syntax. [S1]
+
+## 🧠 핵심 개념 (Core concepts)
+- **Data abstraction** — hiding certain implementation details, showing only essential information to the user; achievable via abstract classes OR interfaces (interfaces deferred to the next chapter). [S1]
+- **`abstract` on a class** — creates a RESTRICTED class that cannot be used to instantiate objects directly (`new Animal()` on an abstract class is a compile error: "Cannot create an instance of the abstract class or interface"). [S1]
+- **`abstract` on a method** — declared with NO body (just a signature ending in `;`); only legal inside an abstract class; the body must be supplied by whichever derived class inherits it, using `override`. [S1]
+- **Mixed abstract classes** — an abstract class can freely combine abstract methods (no body) alongside regular, fully-implemented methods. [S1]
+- **Must be accessed via inheritance** — the ONLY way to use an abstract class's functionality is to inherit from it and instantiate the DERIVED class instead. [S1]
+
+## 📖 세부 내용 (Details)
+- Illegal direct instantiation: `abstract class Animal { public abstract void animalSound(); public void sleep() { Console.WriteLine("Zzz"); } } ... Animal myObj = new Animal(); // Error`. [S1]
+- Full working example (Animal converted from the Polymorphism chapter into an abstract class): `abstract class Animal { public abstract void animalSound(); public void sleep() { Console.WriteLine("Zzz"); } } class Pig : Animal { public override void animalSound() { Console.WriteLine("The pig says: wee wee"); } } ... Pig myPig = new Pig(); myPig.animalSound(); myPig.sleep();` — the abstract method's body comes entirely from `Pig`, while `sleep()` (a regular method) is inherited unchanged. [S1]
+- Purpose stated directly: achieving security by hiding certain details and showing only the important parts of an object. [S1]
+
+## ⚖️ 모순 및 업데이트 (Contradictions & updates)
+- **abstract가 클래스에도 명시적 키워드로 붙음**: C++는 순수 가상 함수(`virtual void f() = 0;`) 하나만 있어도 클래스가 암묵적으로 추상 클래스가 되고 별도의 "추상 클래스" 키워드가 없었지만, C#은 클래스 자체에도 `abstract` 키워드를 명시적으로 붙여야 한다는 점이 확인됨 — 같은 제약(인스턴스화 불가, 상속 필수, 파생 클래스가 반드시 구현 제공)을 표현하는 방식이 암묵적(C++) vs 명시적(C#)으로 다름. [S1]
+- **Polymorphism 챕터의 Animal 예제가 그대로 재사용됨**: 새로운 예제를 만들지 않고 직전 Polymorphism 챕터의 Animal/Pig 예제를 abstract로 변환해 재사용한다는 점이 확인됨 — 개념을 처음부터 다시 설명하지 않고 이미 익힌 코드를 확장하는 방식. [S1]
+
+## 🛠️ 적용 사례 (Applied in summary)
+추상 메서드 animalSound()와 일반 메서드 sleep()을 함께 가진 abstract class Animal을 Pig가 상속해 animalSound()의 몸체만 제공하고 sleep()은 그대로 물려받아 쓰는 예제가 원문에서 직접 실전 활용 사례로 제시됨. [S1]
+
+## 💻 코드 패턴 (Code patterns)
+Abstract class mixing an abstract method (no body) and a regular method (C#):
+```csharp
+abstract class Animal
+{
+    public abstract void animalSound();  // no body -- must be overridden
+    public void sleep()                   // regular method -- inherited as-is
+    {
+        Console.WriteLine("Zzz");
+    }
+}
+class Pig : Animal
+{
+    public override void animalSound()
+    {
+        Console.WriteLine("The pig says: wee wee");
+    }
+}
+
+Pig myPig = new Pig();
+myPig.animalSound(); // "The pig says: wee wee"
+myPig.sleep();        // "Zzz"
+```
+
+## ✅ 검증 상태 및 신뢰도
+- **상태:** draft
+- **검증 단계:** conceptual
+- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
+- **신뢰 점수:** 0.85
+- **중복 검사 결과:** 신규 생성 (New discovery)
+
+## 🔗 지식 그래프 (Knowledge Graph)
+- **상위/루트:** [[C# Tutorial]]
+- **관련 개념:** [[CSharp Polymorphism]], [[CSharp Interface]], [[CPP Templates]]
+- **참조 맥락:** Polymorphism & Abstract 섹션의 마지막 챕터 — Interface 섹션으로 이어짐.
+
+## 📚 출처 (Sources)
+- [S1] W3Schools — C# Abstraction — https://www.w3schools.com/cs/cs_abstract.php
+
+## 📝 변경 이력 (Change history)
+- 2026-07-04: Initial draft synthesized from the W3Schools "C# Abstraction" page (Astra wiki-curation, P-Reinforce v3.1 format).