refactor(topics): 멀티 에이전트용 지식 재편 — _Common(공통 기본기) + Domain_* 구조

에이전트 8종(대화형/프로그래머 C·S/디자이너/설계자/기획자/QA/PD/PM)에게 [공통 기본 능력 + 롤별 Specialty] 2층으로 지식을 주입하기 위한 재분류. 문서 내용·포맷은 무수정, 폴더 이동만 (6,372개 문서 수 보존 확인). - Topic_Programming → Domain_Programming (내부 구조 보존) - Topic_Graphic → Domain_Design - Topic_Business → Domain_Product - Topic_General → Domain_General - _Common 신설: Math(구 Topic_Math_Specialty), Reasoning(구 General/From_Thinking & Reasoning), Reasoning_Creativity(구 General/From_창의성), Communication(Poetic_Blog_Writing + From_writing) - 타 도메인의 From_* 폴더는 유지 (출처 표기일 뿐, 이미 도메인에 맞게 분류된 문서) - 빈 폴더 정리 (memory/procedures) - 에이전트→폴더 매핑은 workspace의 .astra/agent-knowledge-map.json (9개 에이전트) Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-11 11:05:56 +09:00
parent 6549ead309
commit c24165b8bc
6193 changed files with 1717 additions and 31 deletions
@@ -0,0 +1,71 @@
+---
+id: c-null
+title: "C NULL"
+category: "Programming_Language"
+status: "draft"
+verification_status: "conceptual"
+canonical_id: ""
+aliases: ["null pointer", "malloc NULL check", "C NULL"]
+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", "null", "pointers"]
+raw_sources: ["https://www.w3schools.com/c/c_null.php"]
+applied_in: []
+github_commit: ""
+---
+
+# [[C NULL]]
+
+## 🎯 한 줄 통찰 (One-line insight)
+`NULL` is the single unifying failure signal shared by two completely unrelated operations — `fopen()` (file access) and `malloc()` (memory allocation) — meaning the SAME defensive pattern (`if (ptr == NULL) { ...handle error... }`) applies whether the resource that might not exist is a file on disk or a block of RAM, because both operations return an ordinary pointer that's simply set to NULL on failure rather than raising any special error mechanism. [S1]
+
+## 🧠 핵심 개념 (Core concepts)
+- **`NULL`** — represents a "null pointer": a pointer that points to nothing/nowhere. [S1]
+- **Failure signal, not an exception** — many C functions (`fopen()`, `malloc()`) return `NULL` when they fail, rather than throwing any error (since C has no exceptions). [S1]
+- **Universal safety check** — comparing any pointer to `NULL` before using it prevents crashes from accessing invalid memory. [S1]
+- **Same pattern across different resources** — the identical `if (ptr == NULL)` check applies whether guarding against a missing file OR a failed memory allocation. [S1]
+
+## 📖 세부 내용 (Details)
+- File-open failure check: `FILE *fptr = fopen("nothing.txt", "r"); if (fptr == NULL) { printf("Could not open file.\n"); return 1; }`. [S1]
+- Memory-allocation failure check (deliberately requesting an absurd amount): `int *numbers = (int*) malloc(100000000000000 * sizeof(int)); if (numbers == NULL) { printf("Memory allocation failed.\n"); return 1; }`. [S1]
+
+## ⚖️ 모순 및 업데이트 (Contradictions & updates)
+- **NULL 체크는 사용 전 필수 습관**: 크래시를 피하려면 포인터를 사용하기 전 항상 NULL인지 확인해야 한다는 점이 팁으로 강조되며, fopen()과 malloc() 모두 같은 방식으로 실패를 알린다는 공통점이 확인됨. [S1]
+
+## 🛠️ 적용 사례 (Applied in summary)
+현재 발견된 실제 적용 사례가 없습니다 — 지나치게 큰 메모리를 요청해 malloc()이 실패하는 상황을 의도적으로 재현한 예제가 NULL 체크의 실전 필요성을 직접 보여준다. [S1]
+
+## 💻 코드 패턴 (Code patterns)
+The same NULL-check pattern applying to both file access and memory allocation (C):
+```c
+// File access failure
+FILE *fptr = fopen("nothing.txt", "r");
+if (fptr == NULL) { printf("Could not open file.\n"); return 1; }
+
+// Memory allocation failure
+int *numbers = (int*) malloc(100000000000000 * sizeof(int));
+if (numbers == NULL) { printf("Memory allocation failed.\n"); return 1; }
+```
+
+## ✅ 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 Macros]], [[C Memory Deallocate]], [[C Error Handling]], [[C Newline]]
+- **참조 맥락:** NULL — 줄바꿈(Newline) 챕터로 이어짐.
+
+## 📚 출처 (Sources)
+- [S1] W3Schools — C NULL — https://www.w3schools.com/c/c_null.php
+
+## 📝 변경 이력 (Change history)
+- 2026-07-04: Initial draft synthesized from the W3Schools "C NULL" page (Astra wiki-curation, P-Reinforce v3.1 format).