---
id: php-regex
title: "PHP RegEx"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["regular expressions", "PHP 정규표현식"]
duplicate_of: ""
source_trust_level: "B"
confidence_score: 0.88
created_at: 2026-07-04
updated_at: 2026-07-04
review_reason: ""
merge_history: []
tags: ["php", "programming", "w3schools", "regex"]
raw_sources: ["https://www.w3schools.com/php/php_regex.asp"]
applied_in: []
github_commit: ""
---

# [[PHP RegEx]]

## 🎯 한 줄 통찰 (One-line insight)
PHP regex patterns require an explicit DELIMITER character wrapping the pattern (`"/pattern/modifiers"`) — unlike some languages where the pattern is a bare string, and the delimiter itself is swappable (`#`, `~`, etc.) specifically so patterns containing literal `/` characters don't need extra escaping. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Syntax** — `"/pattern/modifiers"` — delimiter + pattern + optional modifiers. [S1]
- **Delimiter rule** — any non-letter/digit/backslash/space character; `/` is most common, but `#`/`~` avoid clashing with patterns containing slashes. [S1]
- **Modifiers** — `i` (case-insensitive), `m` (multiline — `^`/`$` match per-line not just whole-string), `u` (UTF-8 matching). [S1]
- **Bracket expressions** — `[abc]`, `[^abc]`, `[a-z]`, `[A-Z]`, `[0-9]`, etc. [S1]
- **Metacharacters** — `|`, `.`, `^`, `$`, `\d`/`\D`, `\s`/`\S`, `\w`/`\W`, `\b`, `\uxxxx`. [S1]
- **Quantifiers** — `n+`, `n*`, `n?`, `n{3}`, `n{2,5}`, `n{3,}`. [S1]
- **Escaping special characters** — backslash before literal special characters (e.g. `/\?+/` to match one-or-more literal `?`). [S1]

## 📖 세부 내용 (Details)
- Basic pattern: `$exp = "/w3schools/i"; // case-insensitive search for "w3schools"`. [S1]
- Escaping special char: `$pattern = '/\?+/'; // matches one or more literal question marks`. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
소스에서 모순되는 정보는 발견되지 않음.

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — 패턴에 슬래시가 포함될 때 #나 ~로 구분자를 바꾸는 것이 실전에서 자주 쓰이는 관행이다. [S1]

## 💻 코드 패턴 (Code patterns)
Case-insensitive regex pattern (PHP):
```php
$exp = "/w3schools/i";
```

## ✅ 검증 상태 및 신뢰도
- **상태:** draft
- **검증 단계:** conceptual
- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
- **신뢰 점수:** 0.88
- **중복 검사 결과:** 신규 생성 (New discovery)

## 🔗 지식 그래프 (Knowledge Graph)
- **상위/루트:** [[PHP Tutorial]]
- **관련 개념:** [[PHP RegEx Functions]], [[PHP Superglobals Get]], [[PHP Form Validation]]
- **참조 맥락:** 정규표현식 문법 기초 — 정규표현식 함수(RegEx Functions) 챕터로 직접 이어짐.

## 📚 출처 (Sources)
- [S1] W3Schools — PHP Regular Expressions — https://www.w3schools.com/php/php_regex.asp

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