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69 lines
3.4 KiB
Markdown
69 lines
3.4 KiB
Markdown
---
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id: php-strings
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title: "PHP Strings"
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category: "Programming_Language"
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status: "draft"
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verification_status: "conceptual"
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canonical_id: ""
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aliases: ["single vs double quotes", "PHP 문자열"]
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duplicate_of: ""
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source_trust_level: "B"
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confidence_score: 0.9
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created_at: 2026-07-04
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updated_at: 2026-07-04
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review_reason: ""
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merge_history: []
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tags: ["php", "programming", "w3schools", "strings", "quotes"]
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raw_sources: ["https://www.w3schools.com/php/php_string.asp"]
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applied_in: []
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github_commit: ""
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---
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# [[PHP Strings]]
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## 🎯 한 줄 통찰 (One-line insight)
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Double and single quotes are NOT interchangeable in PHP — double quotes interpolate variables and support rich escape sequences (`\n`, `\t`) at a slight performance cost, while single quotes output everything literally (even `$x` prints as `$x`, not its value) and only support `\'`/`\\`, making single quotes both faster and safer for constant strings with no variables. [S1]
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## 🧠 핵심 개념 (Core concepts)
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- **Double quotes** — substitute variable values; support many escape sequences (`\n`, `\r`, `\t`, `\$`, `\"`). [S1]
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- **Single quotes** — output text literally, including `$var` syntax as-is; only `\'` and `\\` are recognized escapes. [S1]
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- **Performance** — single quotes are slightly faster (no parsing needed for variables/escapes). [S1]
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- **Readability trade-off** — double quotes avoid concatenation clutter when many variables are embedded; single quotes are cleaner for constant strings. [S1]
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## 📖 세부 내용 (Details)
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- Variable substitution (double): `$x = "John"; echo "Hello $x"; // Hello John`. [S1]
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- No substitution (single): `$x = "John"; echo 'Hello $x'; // Hello $x`. [S1]
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- Escape sequence comparison: `echo "Hello $x\n"; echo "\tHow are you?\n";` (double, both work) vs. `echo 'Hello $x\n'; echo '\tHow are you?\n';` (single, literal output including the backslash sequences). [S1]
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## ⚖️ 모순 및 업데이트 (Contradictions & updates)
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- **작은따옴표의 리터럴 출력**: $x 같은 변수 구문조차 작은따옴표 안에서는 값으로 치환되지 않고 문자 그대로 출력된다는 점이 예제로 명확히 검증됨. [S1]
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## 🛠️ 적용 사례 (Applied in summary)
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현재 발견된 실제 적용 사례가 없습니다 — 변수가 많은 문자열에는 큰따옴표, 상수 문자열에는 작은따옴표를 쓰는 것이 실전 코드 스타일의 일반적 관행이다. [S1]
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## 💻 코드 패턴 (Code patterns)
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Single quotes output variables literally (PHP):
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```php
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$x = "John";
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echo "Hello $x"; // Hello John (double quotes interpolate)
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echo 'Hello $x'; // Hello $x (single quotes do not)
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```
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## ✅ 검증 상태 및 신뢰도
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- **상태:** draft
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- **검증 단계:** conceptual
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- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
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- **신뢰 점수:** 0.90
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- **중복 검사 결과:** 신규 생성 (New discovery)
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## 🔗 지식 그래프 (Knowledge Graph)
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- **상위/루트:** [[PHP Tutorial]]
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- **관련 개념:** [[PHP String Functions]], [[PHP String Concatenate]], [[PHP String Escape]]
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- **참조 맥락:** 문자열 기초(따옴표 차이) — 문자열 함수 챕터로 이어짐.
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## 📚 출처 (Sources)
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- [S1] W3Schools — PHP Strings — https://www.w3schools.com/php/php_string.asp
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## 📝 변경 이력 (Change history)
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- 2026-07-04: Initial draft synthesized from the W3Schools "PHP Strings" page (Astra wiki-curation, P-Reinforce v3.1 format).
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