2nd/10_Wiki/Topic_Programming/Topic_C/C_Structs.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
c-structs	C Structures (structs)	Programming_Language	draft	conceptual		struct keyword dot syntax C 구조체		B	0.87	2026-07-04	2026-07-04			c programming-language w3schools structs	https://www.w3schools.com/c/c_structs.php

C Structures (structs)

🎯 한 줄 통찰 (One-line insight)

Directly assigning a string literal to a struct's char[] member (s1.myString = "Some text";) produces a compile ERROR ("assignment to expression with array type") — the exact same restriction from the Strings chapter (arrays can't be reassigned wholesale) applies inside structs too, requiring strcpy() UNLESS the assignment happens at declaration time using the comma-separated initializer syntax, which is the one place string literals ARE allowed directly. [S1]

🧠 핵심 개념 (Core concepts)

• Structure (struct) — groups multiple MIXED-type variables ("members") into one unit, unlike arrays which require a single uniform type. [S1]
• Declaration + variable creation — the struct Name {...}; block only defines the TEMPLATE; you must separately declare struct Name variableName; to create an actual instance. [S1]
• Dot syntax (.) — accesses/assigns individual members (s1.myNum = 13;). [S1]
• String members require strcpy() — direct assignment (s1.myString = "text";) fails to compile; use strcpy(s1.myString, "text"); instead. [S1]
• Initializer-list exception — at DECLARATION time, struct myStructure s1 = {13, 'B', "Some text"}; allows string literals directly, no strcpy() needed — values must be listed in the same order as the members were declared. [S1]
• Struct-to-struct copy — s2 = s1; copies ALL members at once, including string arrays, without needing strcpy() per-field. [S1]
• Template reuse — one struct definition (e.g. Car) can be instantiated repeatedly with different values (car1, car2, car3), avoiding separate ad-hoc variable sets per entity. [S1]

📖 세부 내용 (Details)

• The string-assignment error case: s1.myString = "Some text"; // error: assignment to expression with array type. [S1]
• The strcpy() fix: strcpy(s1.myString, "Some text");. [S1]
• Initializer-list shortcut bypassing strcpy(): struct myStructure s1 = {13, 'B', "Some text"};. [S1]
• Real-life template reuse: struct Car { char brand[30]; char model[30]; int year; }; struct Car car1 = {"BMW", "X5", 1999}; struct Car car2 = {"Ford", "Mustang", 1969};. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

• 문자열 멤버 직접 대입 불가: 구조체 안의 char 배열 멤버에도 배열 챕터와 동일한 제약이 적용되어 strcpy()가 필요하지만, 선언 시 초기화 리스트({...}) 문법에서는 예외적으로 문자열 리터럴을 직접 쓸 수 있다는 점이 확인됨. [S1]

🛠️ 적용 사례 (Applied in summary)

Car 구조체 하나로 BMW/Ford/Toyota 세 대의 서로 다른 자동차 정보를 저장하는 예제가 원문에서 직접 실전 활용 사례로 제시됨(하나의 템플릿, 여러 인스턴스). [S1]

💻 코드 패턴 (Code patterns)

One struct template reused for multiple distinct real-world entities (C):

struct Car {
  char brand[30];
  char model[30];
  int year;
};
int main() {
  struct Car car1 = {"BMW", "X5", 1999};
  struct Car car2 = {"Ford", "Mustang", 1969};
  printf("%s %s %d\n", car1.brand, car1.model, car1.year);
  return 0;
}

✅ 검증 상태 및 신뢰도

• 상태: draft
• 검증 단계: conceptual
• 출처 신뢰도: B (W3Schools — widely used educational reference, not a primary standards body)
• 신뢰 점수: 0.87
• 중복 검사 결과: 신규 생성 (New discovery)

🔗 지식 그래프 (Knowledge Graph)

• 상위/루트: C Tutorial
• 관련 개념: C Arrays RealLife, C Strings Functions, C Structs Nested
• 참조 맥락: 구조체 섹션 첫 챕터 — 중첩 구조체(Structs Nested) 챕터로 이어짐.

📚 출처 (Sources)

• [S1] W3Schools — C Structures (structs) — https://www.w3schools.com/c/c_structs.php

📝 변경 이력 (Change history)

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