---
id: python-nested-if
title: "Python Nested If"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["Nested If Statements", "파이썬 중첩 조건문"]
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", "if", "nested"]
raw_sources: ["https://www.w3schools.com/python/python_if_nested_if.asp"]
applied_in: []
github_commit: ""
---

# [[Python Nested If]]

## 🎯 한 줄 통찰 (One-line insight)
Nesting an if inside another if lets the inner condition depend on the outer one being true first, and it's interchangeable with `and` when both conditions are equally simple — nesting wins when the inner logic is genuinely conditional on the outer branch. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Nested if** — an if statement inside another if statement; the inner one only runs when the outer condition is true. [S1]
- **Multiple nesting levels** — legal to any depth, but readability degrades quickly with too many levels. [S1]
- **Nested if vs. `and`** — `if temperature > 20: if is_sunny: ...` is equivalent to `if temperature > 20 and is_sunny: ...` when there's no independent action tied to just the outer condition. [S1]

## 🧩 추출된 패턴 (Extracted patterns)
- **When to nest vs. combine with `and`** — use nested if when the inner logic is complex or genuinely depends on the outer condition (e.g. different messages at each level); use `and` when both conditions are simple and equally weighted. [S1]

## 📖 세부 내용 (Details)
- Basic nesting: `if x > 10: print("Above ten,"); if x > 20: print("and also above 20!") else: print("but not above 20.")`. [S1]
- Three-level nesting: score → attendance → submitted, each gating the next. [S1]
- Equivalent forms: `if temperature > 20: if is_sunny: ...` ≡ `if temperature > 20 and is_sunny: ...`. [S1]

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

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — 로그인 검증(username→password→is_active)처럼 단계적으로 좁혀지는 조건 체크에 전형적으로 쓰인다. [S1]

## 💻 코드 패턴 (Code patterns)
Nested if for step-wise validation (Python):
```python
username = "Emil"
password = "python123"
is_active = True
if username:
    if password:
        if is_active:
            print("Login successful")
        else:
            print("Account is not active")
    else:
        print("Password required")
else:
    print("Username required")
```

## ✅ 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 If Statement]], [[Python Operators Logical]], [[Python Elif]]
- **참조 맥락:** 단계적 조건 분기의 표준 패턴 — `and` 연산자와 상호 대체 가능한 경우가 많다.

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

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