---
id: cpp-access-specifiers
title: "C++ Access Specifiers"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["public private protected", "default is private", "C++ 접근 지정자"]
duplicate_of: ""
source_trust_level: "B"
confidence_score: 0.87
created_at: 2026-07-04
updated_at: 2026-07-04
review_reason: ""
merge_history: []
tags: ["cpp", "programming-language", "w3schools", "oop", "access-specifiers"]
raw_sources: ["https://www.w3schools.com/cpp/cpp_access_specifiers.asp"]
applied_in: []
github_commit: ""
---

# [[CPP Access Specifiers]]

## 🎯 한 줄 통찰 (One-line insight)
If a class member is declared with NO access specifier at all, it defaults to `private` — the exact behavior the earlier Classes chapter's `public:` requirement was silently protecting against — meaning every class example up to this point that used `public:` was actively OVERRIDING C++'s default visibility, not merely adding an optional label; omitting it entirely would have made those attributes inaccessible from outside. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Three access specifiers** — `public` (accessible from outside the class), `private` (NOT accessible from outside), `protected` (not accessible from outside, but accessible in INHERITED/child classes). [S1]
- **Default access is `private`** — a class with no explicit access specifier makes ALL its members private automatically. [S1]
- **Private-by-default as good practice** — declaring attributes `private` "as often as you can" reduces the chance of accidental misuse; this is the core ingredient of Encapsulation (next chapter). [S1]
- **Real-life analogy** — public = front door (anyone can enter); private = locked drawer (only the owner); protected = family-only room (children/subclasses can enter, others cannot). [S1]

## 📖 세부 내용 (Details)
- Mixed public/private members and the resulting access error: `class MyClass { public: int x; private: int y; }; MyClass myObj; myObj.x = 25; // Allowed myObj.y = 50; // error: y is private`. [S1]
- Default-private class with no explicit specifier: `class MyClass { int x; int y; }; // both x and y are private by default`. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
- **접근 지정자 생략 시 기본값은 private**: 이전 Classes 챕터에서 사용된 public:이 단순한 선택적 표시가 아니라, 생략 시 기본으로 적용되는 private를 의도적으로 override한 것이었음이 이 챕터에서 명확히 확인됨. [S1]

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — 클래스 속성을 가능한 한 private으로 선언하는 것이 실전 코드에서 좋은 관행으로 권장되며, 이는 다음 챕터(Encapsulation)의 핵심 재료가 된다. [S1]

## 💻 코드 패턴 (Code patterns)
Mixed public and private members, with the resulting compile error on private access (C++):
```cpp
class MyClass {
public:    // Public access specifier
  int x;   // Public attribute
private:   // Private access specifier
  int y;   // Private attribute
};
int main() {
  MyClass myObj;
  myObj.x = 25;  // Allowed (public)
  myObj.y = 50;  // error: y is private
  return 0;
}
```

## ✅ 검증 상태 및 신뢰도
- **상태:** draft
- **검증 단계:** conceptual
- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
- **신뢰 점수:** 0.87
- **중복 검사 결과:** 신규 생성 (New discovery)

## 🔗 지식 그래프 (Knowledge Graph)
- **상위/루트:** [[C++ Tutorial]]
- **관련 개념:** [[CPP Constructors Overloading]], [[CPP Encapsulation]], [[CPP Inheritance Access]]
- **참조 맥락:** 접근 지정자 — 캡슐화(Encapsulation) 챕터로 이어짐, protected는 상속 접근(Inheritance Access) 챕터와 직접 연결.

## 📚 출처 (Sources)
- [S1] W3Schools — C++ Access Specifiers — https://www.w3schools.com/cpp/cpp_access_specifiers.asp

## 📝 변경 이력 (Change history)
- 2026-07-04: Initial draft synthesized from the W3Schools "C++ Access Specifiers" page (Astra wiki-curation, P-Reinforce v3.1 format).