2nd/10_Wiki/Topic_Programming/Topic_C/C_Functions_Pointers.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-functions-pointers	C Function Pointer	Programming_Language	draft	conceptual		pointer to function function pointer array C 함수 포인터		B	0.87	2026-07-04	2026-07-04			c programming-language w3schools functions function-pointers	https://www.w3schools.com/c/c_functions_pointers.php

C Function Pointer

🎯 한 줄 통찰 (One-line insight)

A function's NAME already acts as a pointer to its own code, even before you declare any explicit function-pointer variable — ptr = add; and ptr = &add; are shown to be IDENTICAL, meaning add (bare, no parentheses) is already an address in the same sense &myAge was an address for a variable, and declaring int (*ptr)(int, int) just gives you a variable that can hold, reassign, and pass around that already-existing address. [S1]

🧠 핵심 개념 (Core concepts)

• Function pointer declaration — returnType (*pointerName)(paramType1, paramType2, ...); (parentheses around *pointerName are required). [S1]
• Assignment equivalence — ptr = add; and ptr = &add; do the same thing, since a function's name is already its address. [S1]
• Call equivalence — ptr(5, 3); and (*ptr)(5, 3); both correctly call the pointed-to function. [S1]
• Choosing behavior at RUNTIME — unlike a normal function call (fixed at compile time), a function pointer lets the program decide WHICH function to run while it's already executing. [S1]
• Function pointer array — storing multiple function pointers in one array (void (*operations[3])() = {add, subtract, multiply};) enables selecting a function by INDEX, e.g. from user input, powering menus/calculators. [S1]

📖 세부 내용 (Details)

• Basic function pointer declaration, assignment, and call: int add(int a, int b) { return a + b; } int (*ptr)(int, int) = add; int result = ptr(5, 3); // same as add(5,3). [S1]
• Passing a function pointer as an argument (a callback): void greet(void (*func)()) { func(); } greet(greetMorning); greet(greetEvening);. [S1]
• A calculator selecting among functions by user-entered index: void (*operations[3])(int, int) = { add, subtract, multiply }; scanf("%d", &choice); operations[choice](x, y);. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

• 함수 이름은 이미 포인터: ptr = add와 ptr = &add가 완전히 동일하게 작동한다는 점에서, 함수 이름 자체가 이미 메모리상 코드 시작 주소를 가리키는 포인터 역할을 하고 있음이 확인됨. [S1]

🛠️ 적용 사례 (Applied in summary)

사용자가 숫자를 입력해 덧셈/뺄셈/곱셈 중 하나를 선택하는 계산기 예제가 원문에서 직접 실전 활용 사례로 제시됨(함수 포인터 배열 + scanf 조합). [S1]

💻 코드 패턴 (Code patterns)

Selecting which function to run at runtime via a function pointer array indexed by user input (C):

void add(int a, int b) { printf("Result: %d\n", a + b); }
void subtract(int a, int b) { printf("Result: %d\n", a - b); }
void multiply(int a, int b) { printf("Result: %d\n", a * b); }
int main() {
  int choice, x = 10, y = 5;
  void (*operations[3])(int, int) = { add, subtract, multiply };
  scanf("%d", &choice);
  if (choice >= 0 && choice < 3) {
    operations[choice](x, y);
  }
  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 Functions Recursion, C Pointers, C Functions Callback
• 참조 맥락: 함수 포인터 — 콜백 함수(Functions Callback) 챕터로 이어짐.

📚 출처 (Sources)

• [S1] W3Schools — C Function Pointer — https://www.w3schools.com/c/c_functions_pointers.php

📝 변경 이력 (Change history)

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