docs(10_Wiki): Dev 폴더 누락분 반영 — Topic_Programming으로 통합

이전 재구성 작업에서 Dev/ 폴더가 누락되었던 것을 반영. - Dev/Topic_Programming(중첩 폴더, 78개)은 Dev 자체 최상위 폴더들 (Architecture/Conventions/Engineering_Intelligence 등)과 완전 중복이라 제거. - Dev 최상위 엔지니어링 지식 폴더(Architecture/Conventions/Engineering_Intelligence/ Failure_Library/Generalized_Principles/Language/Pattern_Catalog/Platform_Guides/ Subsystems, 77개)는 이미 Topic_Programming/Topic_Programming에 더 최신 버전이 존재해 중복 제거(고유 콘텐츠 1개는 예외 처리하여 이동 보존). - Dev의 W3Schools 언어 튜토리얼 폴더(Topic_C/CPP/CSS/CSharp/HOWTO/HTML/Java/ JavaScript/PHP/Python/SQL/W3CSS, 1201개)는 전부 Topic_Programming 하위로 이동. - 에이전트 운영 상태(.astra/docs)는 그대로 유지, 콘텐츠 폴더만 정리. - Topic_Programming 최종 문서 수: 2784 → 3985.
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+---
+id: c-date-time
+title: "C Date and Time"
+category: "Programming_Language"
+status: "draft"
+verification_status: "conceptual"
+canonical_id: ""
+aliases: ["time.h", "struct tm", "strftime", "C 날짜와 시간"]
+duplicate_of: ""
+source_trust_level: "B"
+confidence_score: 0.86
+created_at: 2026-07-04
+updated_at: 2026-07-04
+review_reason: ""
+merge_history: []
+tags: ["c", "programming-language", "w3schools", "date-time", "time.h"]
+raw_sources: ["https://www.w3schools.com/c/c_date_time.php"]
+applied_in: []
+github_commit: ""
+---
+
+# [[C Date and Time]]
+
+## 🎯 한 줄 통찰 (One-line insight)
+`struct tm`'s year and month fields are BOTH offset in ways that will silently produce wrong output if you forget to correct them — `tm_year` counts years SINCE 1900 (so you must add 1900 to get the real year) and `tm_mon` is zero-indexed (0 = January, so you must add 1 for a human-readable month) — two unrelated offset conventions bundled into the same struct that both require manual correction before display. [S1]
+
+## 🧠 핵심 개념 (Core concepts)
+- **`time(&var)` / `time(NULL)`** — retrieves the current time as a `time_t` value. [S1]
+- **`ctime(&time_t_value)`** — converts a raw `time_t` into a human-readable string (e.g. "Mon Jun 24 10:15:00 2025"). [S1]
+- **`localtime(&time_t_value)`** — converts a `time_t` into a `struct tm` POINTER, breaking the time into separate fields (year/month/day/hour/minute/second); accessed via `->` since it's a pointer, per the earlier Structs & Pointers rule. [S1]
+- **`tm_year` offset** — stores years SINCE 1900; must add 1900 for the actual calendar year. [S1]
+- **`tm_mon` offset** — zero-indexed (0=January, 11=December); must add 1 for the conventional 1-12 month number. [S1]
+- **`strftime(buffer, size, format, tm_ptr)`** — formats a `struct tm` into a custom string layout (e.g. `"%d-%m-%Y %H:%M:%S"`), writing into a caller-provided buffer. [S1]
+
+## 📖 세부 내용 (Details)
+- Getting and printing the current time as a readable string: `time_t currentTime; time(&currentTime); printf("Current time: %s", ctime(&currentTime));`. [S1]
+- Breaking time into fields with the required offset corrections: `time_t now = time(NULL); struct tm *t = localtime(&now); printf("Year: %d\n", t->tm_year + 1900); printf("Month: %d\n", t->tm_mon + 1); printf("Day: %d\n", t->tm_mday);`. [S1]
+- Custom-formatted timestamp: `char buffer[100]; strftime(buffer, sizeof(buffer), "%d-%m-%Y %H:%M:%S", t); printf("Formatted time: %s\n", buffer);`. [S1]
+
+## ⚖️ 모순 및 업데이트 (Contradictions & updates)
+- **tm_year와 tm_mon의 오프셋 함정**: tm_year는 1900년 기준 경과 연수이므로 실제 연도를 얻으려면 1900을 더해야 하고, tm_mon은 0부터 시작(0=1월)하므로 실제 월을 얻으려면 1을 더해야 한다는 점이 각각 별개의 주의사항으로 명시됨. [S1]
+
+## 🛠️ 적용 사례 (Applied in summary)
+현재 발견된 실제 적용 사례가 없습니다 — 로그 기록, 파일/메시지에 타임스탬프 추가, 실행 시간 측정, 난수 시드 설정 등이 날짜/시간 라이브러리의 대표 활용 목적으로 원문에 직접 나열됨. [S1]
+
+## 💻 코드 패턴 (Code patterns)
+Breaking the current time into fields with the mandatory offset corrections (C):
+```c
+#include <time.h>
+time_t now = time(NULL);
+struct tm *t = localtime(&now);
+printf("Year: %d\n", t->tm_year + 1900); // tm_year counts from 1900
+printf("Month: %d\n", t->tm_mon + 1);    // tm_mon is 0-indexed
+```
+
+## ✅ 검증 상태 및 신뢰도
+- **상태:** draft
+- **검증 단계:** conceptual
+- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
+- **신뢰 점수:** 0.86
+- **중복 검사 결과:** 신규 생성 (New discovery)
+
+## 🔗 지식 그래프 (Knowledge Graph)
+- **상위/루트:** [[C Tutorial]]
+- **관련 개념:** [[C User Input]], [[C Structs Pointers]], [[C Random Numbers]], [[C Errors]]
+- **참조 맥락:** 사용자 입력 및 날짜 섹션 마지막 — 에러 및 디버깅(Errors & Debugging) 섹션으로 이어짐.
+
+## 📚 출처 (Sources)
+- [S1] W3Schools — C Date and Time — https://www.w3schools.com/c/c_date_time.php
+
+## 📝 변경 이력 (Change history)
+- 2026-07-04: Initial draft synthesized from the W3Schools "C Date and Time" page (Astra wiki-curation, P-Reinforce v3.1 format).