2nd/10_Wiki/Topic_Programming/Topic_PHP/PHP_Variables_Scope.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-variables-scope	PHP Variables Scope	Programming_Language	draft	conceptual		PHP 변수 범위 global keyword static keyword		B	0.9	2026-07-04	2026-07-04			php programming w3schools scope	https://www.w3schools.com/php/php_variables_scope.asp

PHP Variables Scope

🎯 한 줄 통찰 (One-line insight)

static variables break the normal "destroyed on function exit" rule — a static local variable retains its value between separate calls to the same function, meaning static $x = 0; $x++; accumulates across calls even though it's still only accessible inside that one function (local scope + persistent state, a combination unique to static). [S1]

🧠 핵심 개념 (Core concepts)

• Global scope — a variable declared outside any function; NOT accessible inside functions by default. [S1]
• Local scope — a variable declared inside a function; created on call, destroyed on function exit. [S1]
• Static scope — static $x = 0; preserves the variable's value across multiple calls to the same function, while remaining local (inaccessible outside). [S1]
• global keyword — inside a function, declares that a name refers to the global variable rather than creating a new local one. [S1]
• $GLOBALS superglobal — an array holding all global variables, accessible and mutable from inside any function without the global keyword. [S1]

📖 세부 내용 (Details)

• Global scope inaccessible inside function: $x = 5; function myTest() { echo "Variable x inside function is: $x"; } // does not print 5. [S1]
• Local scope: function myTest() { $x = 5; echo "Variable x inside function is: $x"; } // $x undefined outside. [S1]
• Static persists across calls: function myTest() { static $x = 0; echo $x; $x++; } myTest(); myTest(); myTest(); // 0 1 2. [S1]
• global keyword: $x = 5; $y = 10; function myTest() { global $x, $y; $y = $x + $y; } myTest(); echo $y; // 15. [S1]
• $GLOBALS equivalent: function myTest() { $GLOBALS['y'] = $GLOBALS['x'] + $GLOBALS['y']; } myTest(); echo $y; // 15. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

• static의 예외적 지속성: 함수 종료 시 일반 지역변수는 삭제되지만 static 변수는 값을 유지하며, 여전히 함수 지역 범위에 한정된다는 이중적 특성이 명시됨. [S1]

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — 호출 횟수를 세는 카운터(static $x)가 정적 스코프 활용의 대표 사례다. [S1]

💻 코드 패턴 (Code patterns)

Static variable persisting across function calls (PHP):

function myTest() {
    static $x = 0;
    echo $x;
    $x++;
}
myTest(); // 0
myTest(); // 1
myTest(); // 2

✅ 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 Variables, PHP Superglobals Globals, PHP Echo Print
• 참조 맥락: 변수 스코프 규칙 — $GLOBALS는 Superglobals 챕터에서 심화.

📚 출처 (Sources)

• [S1] W3Schools — PHP Variable Scope — https://www.w3schools.com/php/php_variables_scope.asp

📝 변경 이력 (Change history)

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