---
id: cpp-scope
title: "C++ Variable Scope"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["local scope", "global scope", "shadowing", "C++ 변수 스코프"]
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: ["cpp", "programming-language", "w3schools", "scope"]
raw_sources: ["https://www.w3schools.com/cpp/cpp_scope.asp"]
applied_in: []
github_commit: ""
---

# [[CPP Variable Scope]]

## 🎯 한 줄 통찰 (One-line insight)
This chapter, and its exact example (a local `x=22` shadowing a global `x=5`), is IDENTICAL to C's Variable Scope chapter — confirming that C++'s scope rules, including the silent-shadowing behavior where same-named local and global variables coexist as two independent variables with no error, are inherited from C completely unmodified. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Scope** — the region where a variable is accessible; local (inside a function) or global (outside any function). [S1]
- **Local scope** — a variable created inside a function only usable within it; error if accessed outside. [S1]
- **Global scope** — accessible from ANY scope, both other functions and `main()`. [S1]
- **Name collision = shadowing, not conflict** — a local variable with the SAME NAME as a global one creates two independent variables; the local one takes precedence inside its function. [S1]
- **Global mutability risk** — any function can silently modify a global, making state harder to reason about. [S1]

## 📖 세부 내용 (Details)
- Same-name shadowing — two independent variables coexist: `int x = 5; void myFunction() { int x = 22; cout << x; // 22, local } int main() { myFunction(); cout << x; // 5, global — untouched }`. [S1]
- A function silently mutating a global: `int x = 5; void myFunction() { cout << ++x; } // x is now 6`. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
- 현재까지 발견된 모순 사항 없음 (No contradictions found in available sources). C 챕터와 완전히 동일한 스코프 규칙(섀도잉, 전역 변수 위험성)이 확인됨.

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — 기존 C++ 프로그램이나 협업 코드에서 전역 변수를 마주칠 가능성이 높으므로 스코프 동작 원리를 이해해두는 것이 실전에서 유용하다고 원문에 명시됨. [S1]

## 💻 코드 패턴 (Code patterns)
A local variable shadowing a global variable of the same name (C++):
```cpp
int x = 5; // global
void myFunction() {
  int x = 22; // local, shadows the global
  cout << x << "\n"; // 22 (local x)
}
int main() {
  myFunction();
  cout << x; // 5 (global x, untouched)
  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:** 0.85
- **중복 검사 결과:** 신규 생성 (New discovery)

## 🔗 지식 그래프 (Knowledge Graph)
- **상위/루트:** [[C++ Tutorial]]
- **관련 개념:** [[CPP Namespaces]], [[CPP User Input]], [[C Scope]]
- **참조 맥락:** 변수 스코프 — 사용자 입력(User Input) 챕터로 이어짐.

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

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