--- id: php-cookies title: "PHP Cookies" category: "Programming_Language" status: "draft" verification_status: "conceptual" canonical_id: "" aliases: ["setcookie()", "$_COOKIE", "PHP 쿠키"] duplicate_of: "" source_trust_level: "B" confidence_score: 0.9 created_at: 2026-07-04 updated_at: 2026-07-04 review_reason: "" merge_history: [] tags: ["php", "programming", "w3schools", "cookies"] raw_sources: ["https://www.w3schools.com/php/php_cookies.asp"] applied_in: [] github_commit: "" --- # [[PHP Cookies]] ## 🎯 한 줄 통찰 (One-line insight) `setcookie()` MUST run before any HTML output, including before the `` tag — this is a hard requirement (not a style preference) because cookies are transmitted as part of the HTTP header, which must be sent before the response body; this is the same constraint sessions have. [S1] ## 🧠 핵심 개념 (Core concepts) - **Cookie** — a small text file the server stores in the browser, resent with every subsequent HTTP request. [S1] - **`setcookie(name, value, expire, path, domain, secure, httponly)`** — only `name` is required; all others optional. [S1] - **Must precede any output** — `setcookie()` must be called before `` or any other output, since cookies are part of the HTTP header. [S1] - **`$_COOKIE`** — superglobal for reading cookie values. [S1] - **Deleting a cookie** — call `setcookie()` again with an expiration time in the PAST. [S1] - **Auto URL-encoding** — cookie values are automatically URL-encoded on send and decoded on receipt (use `setrawcookie()` to opt out). [S1] ## 📖 세부 내용 (Details) - Create + retrieve: `setcookie($cookie_name, $cookie_value, time() + (86400 * 30), "/"); ... if(isset($_COOKIE[$cookie_name])) { echo $_COOKIE[$cookie_name]; }`. [S1] - Modify: re-calling `setcookie()` with a new value overwrites the old one. [S1] - Delete: `setcookie("username", "", time() - 3600); // expiration in the past`. [S1] - Check if cookies enabled: `setcookie("test_cookie", "test", time() + 3600, '/'); ... if(count($_COOKIE) > 0) { echo "Cookies are enabled."; }`. [S1] ## ⚖️ 모순 및 업데이트 (Contradictions & updates) - **출력 전 호출 필수**: setcookie()는 HTTP 헤더의 일부이므로 반드시 태그를 포함한 어떤 출력보다도 먼저 호출되어야 한다는 점이 두 번 강조됨. [S1] ## 🛠️ 적용 사례 (Applied in summary) 현재 발견된 실제 적용 사례가 없습니다 — 30일 만료 쿠키로 사용자 이름을 저장하는 것이 로그인 상태 유지의 대표 실전 사례다. [S1] ## 💻 코드 패턴 (Code patterns) Creating and checking a cookie (PHP): ```php ?> ``` ## ✅ 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 File Upload]], [[PHP Sessions]], [[PHP Superglobals]] - **참조 맥락:** 클라이언트 측 데이터 저장 — 세션(Sessions) 챕터로 직접 이어짐. ## 📚 출처 (Sources) - [S1] W3Schools — PHP Cookies — https://www.w3schools.com/php/php_cookies.asp ## 📝 변경 이력 (Change history) - 2026-07-04: Initial draft synthesized from the W3Schools "PHP Cookies" page (Astra wiki-curation, P-Reinforce v3.1 format).