---
id: c-enums
title: "C Enumeration (enum)"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["enum keyword", "named constants", "C 열거형"]
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: ["c", "programming-language", "w3schools", "enums"]
raw_sources: ["https://www.w3schools.com/c/c_enums.php"]
applied_in: []
github_commit: ""
---

# [[C Enumeration (enum)]]

## 🎯 한 줄 통찰 (One-line insight)
Assigning an explicit value to just ONE enum item cascades forward — `enum Level { LOW = 5, MEDIUM, HIGH };` gives `MEDIUM` the value 6 and `HIGH` the value 7 automatically, without being written explicitly — meaning enum numbering isn't independently assigned per item by default; each unlabeled item simply continues incrementing from whatever the PRECEDING item's value was. [S1]

## 🧠 핵심 개념 (Core concepts)
- **`enum`** — a type representing a group of named, unchangeable constants ("specifically listed" values). [S1]
- **Default numbering** — the first item is 0, the second 1, and so on, unless overridden. [S1]
- **Forward-cascading custom values** — setting one item's value shifts all SUBSEQUENT unlabeled items to continue counting up from it. [S1]
- **Enum as an int under the hood** — printing an enum variable with `%d` shows its underlying integer value, enabling direct use in `switch` statements matched against those integers. [S1]
- **`typedef` with enum** — eliminates needing to write `enum` before the type name every time a variable is declared, a pure readability/brevity improvement. [S1]

## 📖 세부 내용 (Details)
- Default numbering: `enum Level { LOW, MEDIUM, HIGH }; enum Level myVar = MEDIUM; printf("%d", myVar); // 1`. [S1]
- Fully custom values: `enum Level { LOW = 25, MEDIUM = 50, HIGH = 75 };`. [S1]
- Cascading from one custom value: `enum Level { LOW = 5, MEDIUM, HIGH };` — MEDIUM becomes 6, HIGH becomes 7. [S1]
- Enum used in a switch: `enum Level myVar = MEDIUM; switch (myVar) { case 1: ... case 2: ... case 3: ... }` (matching against LOW=1, MEDIUM=2, HIGH=3). [S1]
- typedef shortcut: `typedef enum {MON, TUE, WED, THU, FRI, SAT, SUN} Day; Day today = WED;` instead of `enum Day today = WED;`. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
- **하나의 값 지정이 이후 항목까지 연쇄적으로 영향**: LOW = 5로 지정하면 뒤따르는 MEDIUM, HIGH는 명시하지 않아도 자동으로 6, 7이 된다는 점이 명확히 확인됨 — 각 항목이 독립적으로 0부터 재시작하는 것이 아님. [S1]

## 🛠️ 적용 사례 (Applied in summary)
요일(Day)이나 월과 같이 절대 변하지 않는 값 집합에 enum을 사용하는 것이 실전 활용의 대표 사례로 원문에 직접 제시됨. [S1]

## 💻 코드 패턴 (Code patterns)
Setting one enum value causes subsequent items to cascade forward from it (C):
```c
enum Level {
  LOW = 5,
  MEDIUM, // Now 6
  HIGH    // Now 7
};
```

## ✅ 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:** [[C Structs Pointers]], [[C Switch]], [[C Unions]], [[C Typedef]]
- **참조 맥락:** 열거형 — 유니온(Unions) 챕터로 이어짐, typedef 챕터와 직접 연결.

## 📚 출처 (Sources)
- [S1] W3Schools — C Enumeration (enum) — https://www.w3schools.com/c/c_enums.php

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