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Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-11 11:05:56 +09:00

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id title category status verification_status canonical_id aliases duplicate_of source_trust_level confidence_score created_at updated_at review_reason merge_history tags raw_sources applied_in github_commit
php-strings PHP Strings Programming_Language draft conceptual
single vs double quotes
PHP 문자열
B 0.9 2026-07-04 2026-07-04
php
programming
w3schools
strings
quotes
https://www.w3schools.com/php/php_string.asp

PHP Strings

🎯 한 줄 통찰 (One-line insight)

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]

🧠 핵심 개념 (Core concepts)

  • Double quotes — substitute variable values; support many escape sequences (\n, \r, \t, \$, \"). [S1]
  • Single quotes — output text literally, including $var syntax as-is; only \' and \\ are recognized escapes. [S1]
  • Performance — single quotes are slightly faster (no parsing needed for variables/escapes). [S1]
  • Readability trade-off — double quotes avoid concatenation clutter when many variables are embedded; single quotes are cleaner for constant strings. [S1]

📖 세부 내용 (Details)

  • Variable substitution (double): $x = "John"; echo "Hello $x"; // Hello John. [S1]
  • No substitution (single): $x = "John"; echo 'Hello $x'; // Hello $x. [S1]
  • 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]

⚖️ 모순 및 업데이트 (Contradictions & updates)

  • 작은따옴표의 리터럴 출력: $x 같은 변수 구문조차 작은따옴표 안에서는 값으로 치환되지 않고 문자 그대로 출력된다는 점이 예제로 명확히 검증됨. [S1]

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — 변수가 많은 문자열에는 큰따옴표, 상수 문자열에는 작은따옴표를 쓰는 것이 실전 코드 스타일의 일반적 관행이다. [S1]

💻 코드 패턴 (Code patterns)

Single quotes output variables literally (PHP):

$x = "John";
echo "Hello $x";  // Hello John (double quotes interpolate)
echo 'Hello $x';  // Hello $x  (single quotes do not)

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)

📚 출처 (Sources)

📝 변경 이력 (Change history)

  • 2026-07-04: Initial draft synthesized from the W3Schools "PHP Strings" page (Astra wiki-curation, P-Reinforce v3.1 format).