---
id: python-casting
title: "Python Casting"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["int() float() str()", "파이썬 형변환"]
duplicate_of: ""
source_trust_level: "B"
confidence_score: 0.9
created_at: 2026-07-04
updated_at: 2026-07-04
review_reason: ""
merge_history: []
tags: ["python", "programming", "w3schools", "casting"]
raw_sources: ["https://www.w3schools.com/python/python_casting.asp"]
applied_in: []
github_commit: ""
---

# [[Python Casting]]

## 🎯 한 줄 통찰 (One-line insight)
Because Python's primitive types are themselves classes, casting is done through constructor function calls (int(), float(), str()) rather than a dedicated cast syntax, and int() truncates rather than rounds. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Casting via constructors** — Python is object-oriented and uses classes even for primitive types, so casting means calling a constructor function. [S1]
- **`int()`** — builds an integer from an int/float literal (removing decimals) or a string that represents a whole number. [S1]
- **`float()`** — builds a float from an int/float/string literal representing a float or integer. [S1]
- **`str()`** — builds a string from a wide variety of data types. [S1]

## 🧩 추출된 패턴 (Extracted patterns)
- **`int()` truncates, doesn't round** — `int(2.8)` gives `2`, not `3` — casting a float to int discards the decimal portion rather than rounding to the nearest integer. [S1]

## 📖 세부 내용 (Details)
- Integer casting: `x = int(1); y = int(2.8)  # 2; z = int("3")`. [S1]
- Float casting: `x = float(1); y = float(2.8); z = float("3"); w = float("4.2")`. [S1]
- String casting: `x = str("s1"); y = str(2); z = str(3.0)`. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
소스에서 모순되는 정보는 발견되지 않음.

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — Numbers/Variables 챕터에서 이미 예고된 캐스팅 문법이 여기서 상세화된다. [S1]

## 💻 코드 패턴 (Code patterns)
int() truncates decimals (Python):
```python
x = int(1)    # x will be 1
y = int(2.8)  # y will be 2 (truncated, not rounded)
z = int("3")  # z will be 3
```

## ✅ 검증 상태 및 신뢰도
- **상태:** draft
- **검증 단계:** conceptual
- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
- **신뢰 점수:** 0.90
- **중복 검사 결과:** 신규 생성 (New discovery)

## 🔗 지식 그래프 (Knowledge Graph)
- **상위/루트:** [[Python Tutorial]]
- **관련 개념:** [[Python Variables]], [[Python Numbers]], [[Python Data Types]]
- **참조 맥락:** 타입 간 명시적 변환이 필요할 때 사용 — int() 절삭 동작에 유의.

## 📚 출처 (Sources)
- [S1] W3Schools — Python Casting — https://www.w3schools.com/python/python_casting.asp

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