---
id: cpp-classes
title: "C++ Classes and Objects"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["class keyword", "public access specifier", "attributes", "C++ 클래스와 객체"]
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", "classes"]
raw_sources: ["https://www.w3schools.com/cpp/cpp_classes.asp"]
applied_in: []
github_commit: ""
---

# [[CPP Classes and Objects]]

## 🎯 한 줄 통찰 (One-line insight)
A C++ class LOOKS almost identical to a C struct at first glance — variables grouped inside curly braces, accessed via dot syntax, ending in a semicolon — but requires ONE extra piece C's struct never needed: the `public:` access specifier, meaning without it, class members would default to being INACCESSIBLE from outside the class, a private-by-default behavior structs don't have. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Class** — a user-defined data type; a "blueprint" for creating objects; variables inside are called ATTRIBUTES, functions are called METHODS (collectively "class members"). [S1]
- **`class` keyword** — creates a class, e.g. `class MyClass { ... };` — ending with a semicolon, just like a struct. [S1]
- **`public:` access specifier** — REQUIRED for members to be accessible from outside the class (covered in more depth in a later chapter). [S1]
- **Creating an object** — `MyClass myObj;` instantiates the class; attributes are accessed via dot syntax (`myObj.myNum`). [S1]
- **Multiple objects from one class** — each object maintains its OWN independent set of attribute values. [S1]

## 📖 세부 내용 (Details)
- Basic class with public attributes: `class MyClass { public: int myNum; string myString; };`. [S1]
- Creating an object and setting/reading attributes: `MyClass myObj; myObj.myNum = 15; myObj.myString = "Some text"; cout << myObj.myNum;`. [S1]
- Two independent objects of the same class: `Car carObj1; carObj1.brand = "BMW"; Car carObj2; carObj2.brand = "Ford";` — each object's `brand` is stored separately. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
- **public 접근 지정자가 필수적으로 요구됨**: C의 struct와 겉모습은 비슷하지만, C++ 클래스는 멤버를 클래스 외부에서 접근하려면 public: 접근 지정자를 명시해야 한다는 점이 확인됨(기본은 private) — 이는 다음 섹션(Access Specifiers)에서 더 자세히 다뤄짐. [S1]

## 🛠️ 적용 사례 (Applied in summary)
Car 클래스 하나로 BMW와 Ford 두 대의 서로 다른 자동차 객체를 만드는 예제가 원문에서 직접 실전 활용 사례로 제시됨. [S1]

## 💻 코드 패턴 (Code patterns)
A class with public attributes, instantiated as two independent objects (C++):
```cpp
class Car {
public:
  string brand;
  string model;
  int year;
};
int main() {
  Car carObj1;
  carObj1.brand = "BMW";
  Car carObj2;
  carObj2.brand = "Ford";
  cout << carObj1.brand << "\n" << carObj2.brand;
  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 OOP]], [[CPP Class Methods]], [[C Structs]]
- **참조 맥락:** 클래스와 객체 — 클래스 메서드(Class Methods) 챕터로 이어짐.

## 📚 출처 (Sources)
- [S1] W3Schools — C++ Classes and Objects — https://www.w3schools.com/cpp/cpp_classes.asp

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