---
id: c-structs-pointers
title: "C Structs and Pointers"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["arrow operator", "struct pointer", "C 구조체 포인터"]
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", "structs", "pointers"]
raw_sources: ["https://www.w3schools.com/c/c_structs_pointers.php"]
applied_in: []
github_commit: ""
---

# [[C Structs and Pointers]]

## 🎯 한 줄 통찰 (One-line insight)
Passing a struct pointer into a function is the difference between the function seeing a temporary COPY versus the ORIGINAL — the `updateYear()` example modifies `c->year` inside the function and the change is visible back in `main()` afterward, specifically because a pointer (address) was passed rather than the struct itself, which would have been copied and discarded when the function returned. [S1]

## 🧠 핵심 개념 (Core concepts)
- **`struct Type *ptr`** — declares a pointer to a struct, same `*` syntax as any other pointer type. [S1]
- **`->` (arrow operator)** — REPLACES the dot syntax when accessing members through a pointer; `ptr->member` is required instead of `ptr.member`. [S1]
- **Function mutation via pointer** — passing `&myCar` (the struct's address) lets a function permanently modify the original struct's members, unlike passing the struct by value. [S1]
- **Three motivations for struct pointers** — avoid copying large structs (performance/memory), allow functions to modify the original values, and enable dynamic struct creation via `malloc()` (previewed, covered later in Memory Management). [S1]

## 📖 세부 내용 (Details)
- Basic pointer declaration and arrow-operator access: `struct Car car = {"Toyota", 2020}; struct Car *ptr = &car; printf("Brand: %s\n", ptr->brand); printf("Year: %d\n", ptr->year);`. [S1]
- Function that mutates the original struct via a pointer parameter: `void updateYear(struct Car *c) { c->year = 2025; } int main() { struct Car myCar = {"Toyota", 2020}; updateYear(&myCar); printf("Year: %d\n", myCar.year); }` — prints 2025, not 2020, because the function received the original struct's address. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
- **포인터 접근에는 화살표 연산자 필수**: 구조체 변수는 점(.) 문법을 쓰지만, 포인터를 통한 접근은 반드시 화살표(->) 연산자를 써야 한다는 점이 문법적 차이로 명시됨. [S1]

## 🛠️ 적용 사례 (Applied in summary)
자동차 구조체의 연식(year)을 함수 안에서 포인터를 통해 2025로 변경하고 그 변경이 main()에도 반영되는 예제가 원문에서 직접 실전 활용 사례로 제시됨. [S1]

## 💻 코드 패턴 (Code patterns)
A function permanently modifying the original struct's field via a pointer parameter (C):
```c
struct Car {
  char brand[30];
  int year;
};
void updateYear(struct Car *c) {
  c->year = 2025; // Change the year
}
int main() {
  struct Car myCar = {"Toyota", 2020};
  updateYear(&myCar); // Pass a pointer so the function can change the year
  printf("Year: %d\n", myCar.year); // 2025
  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:** 0.86
- **중복 검사 결과:** 신규 생성 (New discovery)

## 🔗 지식 그래프 (Knowledge Graph)
- **상위/루트:** [[C Tutorial]]
- **관련 개념:** [[C Structs Padding]], [[C Pointers]], [[C Enums]]
- **참조 맥락:** 구조체와 포인터 — 열거형(Enums) 챕터로 이어짐, 포인터(Pointers) 챕터와 직접 연결.

## 📚 출처 (Sources)
- [S1] W3Schools — C Structs and Pointers — https://www.w3schools.com/c/c_structs_pointers.php

## 📝 변경 이력 (Change history)
- 2026-07-04: Initial draft synthesized from the W3Schools "C Structs and Pointers" page (Astra wiki-curation, P-Reinforce v3.1 format).
