---
id: php-switch
title: "PHP Switch"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["PHP 스위치문"]
duplicate_of: ""
source_trust_level: "B"
confidence_score: 0.9
created_at: 2026-07-04
updated_at: 2026-07-04
review_reason: ""
merge_history: []
tags: ["php", "programming", "w3schools", "switch"]
raw_sources: ["https://www.w3schools.com/php/php_switch.asp"]
applied_in: []
github_commit: ""
---

# [[PHP Switch]]

## 🎯 한 줄 통찰 (One-line insight)
Omitting `break` causes "fall-through" that runs the NEXT case's code too, regardless of whether it matches — the source's own example demonstrates this directly: removing `break` from the matched "red" case makes the "blue" case's code execute right after it, even though `$favcolor` is definitely not "blue". [S1]

## 🧠 핵심 개념 (Core concepts)
- **`switch(expression)`** — evaluates once, compares against each `case`. [S1]
- **`break`** — required to stop fall-through into the next case; the LAST case doesn't strictly need it. [S1]
- **Fall-through warning** — omitting break in a non-last case runs the next case's code unconditionally. [S1]
- **`default`** — runs when no case matches. [S1]
- **Combining cases** — stacking multiple `case` labels with no code between them shares one code block. [S1]

## 📖 세부 내용 (Details)
- Basic switch: `switch ($favcolor) { case "red": echo "Your favorite color is red!"; break; case "blue": ...; default: ...; }`. [S1]
- Fall-through demonstration: removing `break` from `case "red":` causes `case "blue":`'s code to also run even though favcolor is "red", not "blue". [S1]
- Combined cases: `case 1: case 2: case 3: case 4: case 5: echo "The week feels so long!"; break; case 6: case 0: echo "Weekends are best!"; break;`. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
- **break 생략 시 폴스루(fall-through) 경고**: 마지막이 아닌 case에서 break를 생략하면 다음 case 코드가 매치 여부와 무관하게 실행된다는 점이 예제로 직접 증명됨. [S1]

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — 요일 그룹(평일/주말)을 case 결합으로 표현하는 것이 실전 활용의 대표 패턴이다. [S1]

## 💻 코드 패턴 (Code patterns)
Combining multiple case labels for shared logic (PHP):
```php
$d = 3;
switch ($d) {
    case 1:
    case 2:
    case 3:
    case 4:
    case 5:
        echo "The week feels so long!";
        break;
    case 6:
    case 0:
        echo "Weekends are best!";
        break;
    default:
        echo "Something went wrong";
}
```

## ✅ 검증 상태 및 신뢰도
- **상태:** draft
- **검증 단계:** conceptual
- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
- **신뢰 점수:** 0.90
- **중복 검사 결과:** 신규 생성 (New discovery)

## 🔗 지식 그래프 (Knowledge Graph)
- **상위/루트:** [[PHP Tutorial]]
- **관련 개념:** [[PHP If Nested]], [[PHP Match]], [[PHP Looping]]
- **참조 맥락:** 다중 분기 구조 — Match 표현식(PHP 8) 챕터로 직접 이어짐.

## 📚 출처 (Sources)
- [S1] W3Schools — PHP switch Statement — https://www.w3schools.com/php/php_switch.asp

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