2nd/10_Wiki/Dev/Topic_PHP/PHP_String_Functions.md

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

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-string-functions	PHP String Functions	Programming_Language	draft	conceptual		strlen strpos str_contains PHP 문자열 함수		B	0.9	2026-07-04	2026-07-04			php programming w3schools strings functions	https://www.w3schools.com/php/php_string_functions.asp

PHP String Functions

🎯 한 줄 통찰 (One-line insight)

str_contains(), str_starts_with(), and str_ends_with() are ALL PHP 8.0+ only — the source explicitly flags this version dependency for each, meaning code targeting older PHP must fall back to strpos() for containment checks, a compatibility gap worth checking before using these convenience functions. [S1]

🧠 핵심 개념 (Core concepts)

• strlen() — returns string length. [S1]
• str_word_count() — counts words in a string. [S1]
• str_contains() (PHP 8.0+) — boolean substring check, case-sensitive. [S1]
• strpos() — returns the position of the first match, or false if not found; case-sensitive; index starts at 0. [S1]
• str_starts_with() / str_ends_with() (PHP 8.0+) — boolean prefix/suffix checks, case-sensitive. [S1]

📖 세부 내용 (Details)

• Length: echo strlen("Hello world!");. [S1]
• Word count: echo str_word_count("Hello world!");. [S1]
• Contains (case-sensitive): $txt = "I really love PHP!"; var_dump(str_contains($txt, "love")); // true; var_dump(str_contains($txt, "Love")); // false. [S1]
• Position search: echo strpos("Hello world!", "world"); // 6. [S1]
• Starts/ends with (case-sensitive): var_dump(str_starts_with($txt, "I really")); // true; var_dump(str_starts_with($txt, "i really")); // false. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

• PHP 8.0 이상 전용 함수: str_contains/str_starts_with/str_ends_with 모두 PHP 8.0부터 사용 가능하며, 구버전에서는 strpos()로 대체해야 함이 각각 명시됨. [S1]

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — 문자열 포함 여부 검사가 사용자 입력 검증 등에서 자주 쓰이는 실전 패턴이다. [S1]

💻 코드 패턴 (Code patterns)

Case-sensitive substring check (PHP 8.0+):

$txt = "I really love PHP!";
var_dump(str_contains($txt, "love")); // true
var_dump(str_contains($txt, "Love")); // false (case-sensitive)

✅ 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 Strings, PHP String Modify, PHP String Slicing
• 참조 맥락: 문자열 검색/검사 함수 — 문자열 변형(Modify) 챕터로 이어짐.

📚 출처 (Sources)

• [S1] W3Schools — PHP String Functions — https://www.w3schools.com/php/php_string_functions.asp

📝 변경 이력 (Change history)

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