---
id: c-fixed-width-ints
title: "C Fixed Width Integers"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["stdint.h", "int32_t uint8_t", "C 고정폭 정수"]
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", "fixed-width-integers", "stdint"]
raw_sources: ["https://www.w3schools.com/c/c_fixed_width_ints.php"]
applied_in: []
github_commit: ""
---

# [[C Fixed Width Integers]]

## 🎯 한 줄 통찰 (One-line insight)
The battery-level example makes the case concrete: since a percentage is always 0-100, using a plain `int` (likely 4 bytes) instead of `uint8_t` (exactly 1 byte) wastes 3 bytes per value for NO benefit — fixed-width types aren't just about portability, they're a deliberate memory-fit-to-range decision that a generic `int` habit obscures. [S1]

## 🧠 핵심 개념 (Core concepts)
- **The portability problem** — `int`, `short`, `long` sizes vary by system/compiler (e.g. `int` might be 2 bytes on one system, 4 on another). [S1]
- **`<stdint.h>` fixed-width types** — `int8_t`/`uint8_t` (1 byte), `int16_t`/`uint16_t` (2 bytes), `int32_t`/`uint32_t` (4 bytes), `int64_t`/`uint64_t` (8 bytes) — guaranteed identical size on every system. [S1]
- **`u` prefix meaning** — unsigned; doubles the maximum positive range compared to the signed version, at the cost of no negative values. [S1]
- **When they matter** — embedded/microcontroller systems, file formats requiring exact byte layouts, and network data exchange needing consistent results across machines. [S1]
- **When they don't matter** — for most everyday programs, a normal `int` is sufficient; fixed-width types are a deliberate choice for specific constraints, not a default habit. [S1]

## 📖 세부 내용 (Details)
- Declaring across all four sizes: `int8_t a = 100; int16_t b = 30000; int32_t c = 2000000; int64_t d = 9000000000;` printed with `%d`/`%d`/`%d`/`%lld` respectively. [S1]
- Battery-level real-life example: `uint8_t battery = 87; printf("Battery level is %u out of 100\n", battery);` — a value naturally bounded 0-255 fits exactly in 1 byte. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
- **고정폭 타입은 일상 프로그래밍에는 불필요**: 대부분의 프로그램에서는 일반 int로 충분하며, 고정폭 타입은 임베디드 시스템/파일 포맷/네트워크 통신처럼 정확한 크기가 중요한 특수 상황에서만 필요하다는 점이 명시됨. [S1]

## 🛠️ 적용 사례 (Applied in summary)
배터리 잔량(0-100%)처럼 값의 범위가 명확히 제한된 경우 uint8_t를 사용해 메모리를 절약하는 것이 실전 임베디드 프로그래밍의 대표 활용 사례로 원문에 직접 제시됨. [S1]

## 💻 코드 패턴 (Code patterns)
Using a 1-byte fixed-width type for a value with a known bounded range (C):
```c
#include <stdio.h>
#include <stdint.h>
int main() {
  uint8_t battery = 87; // battery level percentage, fits in 1 byte
  printf("Battery level is %u out of 100\n", battery);
  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 Storage Classes]], [[C Data Types Extended]], [[C Operators]]
- **참조 맥락:** 상수 및 저장 클래스 섹션 마지막 — 연산자(Operators) 섹션으로 이어짐.

## 📚 출처 (Sources)
- [S1] W3Schools — C Fixed Width Integers — https://www.w3schools.com/c/c_fixed_width_ints.php

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