2nd/10_Wiki/Topics/Domain_Programming/Topic_PHP/PHP_Casting.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-casting	PHP Casting	Programming_Language	draft	conceptual		type casting PHP 타입 캐스팅		B	0.9	2026-07-04	2026-07-04			php programming w3schools casting types	https://www.w3schools.com/php/php_casting.asp

PHP Casting

🎯 한 줄 통찰 (One-line insight)

Casting an object to an array converts its property names into array keys automatically ((array) $myCar turns color/model properties into ["color" => ..., "model" => ...]) — this reversible object↔associative-array relationship is a core mechanic for interoperating between OOP and plain data structures in PHP. [S1]

🧠 핵심 개념 (Core concepts)

• Casting operators — (string), (int), (float), (bool), (array), (object), (unset) (deprecated in 7.2, removed in 8.0). [S1]
• Bool cast rule — 0, NULL, false, "" (empty string) convert to false; everything else (even -1) converts to true. [S1]
• Array cast on scalars — most types become a single-element indexed array. [S1]
• Array cast on objects — becomes an associative array with property names as keys. [S1]
• Object cast on scalars — becomes an object with one property named "scalar". [S1]
• Object cast on arrays — indexed arrays get numeric-index property names; associative arrays keep their keys as property names. [S1]
• NULL casting — the deprecated/removed (unset) operator is replaced by simply assigning NULL directly. [S1]

📖 세부 내용 (Details)

• Bool falsy values: $c = 0; $g = ""; // both cast to false, while $d = -1; // casts to true. [S1]
• Object → array: class Car { public $color; public $model; ... } $myCar = new Car("red", "Volvo"); $myCar = (array) $myCar; var_dump($myCar); // ["color" => "red", "model" => "Volvo"]. [S1]
• Indexed array → object: $a = array("Volvo", "BMW", "Toyota"); $a = (object) $a; // properties named 0, 1, 2. [S1]
• Associative array → object: $b = array("Peter"=>"35", "Ben"=>"37"); $b = (object) $b; // properties named Peter, Ben. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

• (unset) 캐스팅 지원 중단: PHP 7.2.0에서 지원 중단(deprecated), PHP 8.0.0에서 완전히 제거됨 — 대신 변수에 NULL을 직접 할당하는 방식 사용. [S1]

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — 객체를 연관 배열로 변환하는 패턴이 데이터 직렬화/디버깅에서 자주 쓰인다. [S1]

💻 코드 패턴 (Code patterns)

Casting an object to an associative array (PHP):

class Car {
    public $color;
    public $model;
    public function __construct($color, $model) {
        $this->color = $color;
        $this->model = $model;
    }
}
$myCar = new Car("red", "Volvo");
$myCar = (array) $myCar;
var_dump($myCar); // ["color" => "red", "model" => "Volvo"]

✅ 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 Numbers, PHP Data Types, PHP OOP Classes Objects, PHP Arrays
• 참조 맥락: 명시적 타입 변환 — 수학함수(Math) 챕터로 이어짐.

📚 출처 (Sources)

• [S1] W3Schools — PHP Type Casting — https://www.w3schools.com/php/php_casting.asp

📝 변경 이력 (Change history)

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