---
id: cpp-constructors
title: "C++ Constructors"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["constructor rules", "same name as class", "no return type", "C++ 생성자"]
duplicate_of: ""
source_trust_level: "B"
confidence_score: 0.86
created_at: 2026-07-04
updated_at: 2026-07-04
review_reason: ""
merge_history: []
tags: ["cpp", "programming-language", "w3schools", "oop", "constructors"]
raw_sources: ["https://www.w3schools.com/cpp/cpp_constructors.asp"]
applied_in: []
github_commit: ""
---

# [[CPP Constructors]]

## 🎯 한 줄 통찰 (One-line insight)
A constructor breaks TWO rules every other function in C++ follows — it has NO return type at all, "not even void," and its name must be IDENTICAL to the class name — meaning a constructor isn't really "a special kind of function" so much as a fundamentally different syntactic category that happens to look function-shaped, distinguished purely by the compiler recognizing the name-matches-class pattern. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Constructor** — a special method AUTOMATICALLY called when an object is created; runs with zero explicit invocation from the programmer. [S1]
- **Four constructor rules** — same name as the class; NO return type (not even `void`); usually declared `public`; automatically called on object creation. [S1]
- **Constructor with parameters** — sets initial attribute values at creation time (`Car(string x, string y, int z) { brand = x; ... }`), so each object starts pre-configured. [S1]
- **Defined outside the class** — same `::` scope resolution pattern as regular methods. [S1]

## 📖 세부 내용 (Details)
- Basic parameterless constructor: `class MyClass { public: MyClass() { cout << "Hello World!"; } }; MyClass myObj; // triggers the constructor automatically`. [S1]
- Constructor with parameters setting initial attributes: `class Car { public: string brand; string model; int year; Car(string x, string y, int z) { brand = x; model = y; year = z; } }; Car carObj1("BMW", "X5", 1999);`. [S1]
- Defined outside the class via `::`: `Car(string x, string y, int z); // declaration Car::Car(string x, string y, int z) { brand = x; model = y; year = z; } // definition`. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
- **생성자는 반환 타입이 전혀 없음**: void조차 쓰지 않는다는 점과 클래스 이름과 완전히 동일해야 한다는 점이 다른 모든 함수/메서드와 근본적으로 다른 두 가지 규칙으로 명시됨. [S1]

## 🛠️ 적용 사례 (Applied in summary)
피자 주문 비유("생성자는 소스·치즈·토핑을 미리 얹어주는 요리사")가 생성자가 객체 생성 시 자동으로 초기 설정을 마쳐준다는 개념을 직관적으로 설명하는 실전 비유로 원문에 제시됨. [S1]

## 💻 코드 패턴 (Code patterns)
A constructor with parameters setting initial attribute values automatically (C++):
```cpp
class Car {
public:
  string brand;
  string model;
  int year;
  Car(string x, string y, int z) { // Constructor with parameters
    brand = x;
    model = y;
    year = z;
  }
};
int main() {
  Car carObj1("BMW", "X5", 1999); // constructor runs automatically
  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:** 0.86
- **중복 검사 결과:** 신규 생성 (New discovery)

## 🔗 지식 그래프 (Knowledge Graph)
- **상위/루트:** [[C++ Tutorial]]
- **관련 개념:** [[CPP Class Methods]], [[CPP Constructors Overloading]], [[CPP Function Overloading]]
- **참조 맥락:** 생성자 — 생성자 오버로딩(Constructors Overloading) 챕터로 이어짐.

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

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