---
id: python-for-loops
title: "Python For Loops"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["for loop", "range()", "nested loops", "파이썬 for 반복문"]
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", "for", "loop", "range"]
raw_sources: ["https://www.w3schools.com/python/python_for_loops.asp"]
applied_in: []
github_commit: ""
---

# [[Python For Loops]]

## 🎯 한 줄 통찰 (One-line insight)
Python's for loop is an iterator over any sequence (list, tuple, dict, set, string) rather than a counter-based loop like in C-style languages, and `range(6)` yields 0 through 5, not 0 through 6 — the end value is always exclusive. [S1]

## 🧠 핵심 개념 (Core concepts)
- **`for` loop** — iterates over a sequence (list, tuple, dictionary, set, string); no indexing variable needed. [S1]
- **Iterates any sequence, including strings** — `for x in "banana":` loops over characters. [S1]
- **`break`** — exits the loop early. [S1]
- **`continue`** — skips to the next iteration. [S1]
- **`range()`** — generates a number sequence; default starts at 0, increments by 1, end value EXCLUSIVE (`range(6)` = 0..5). [S1]
- **`range(start, stop)`** — custom start. [S1]
- **`range(start, stop, step)`** — custom increment. [S1]
- **`else`** — runs when the loop finishes normally; skipped if stopped by `break` (same rule as while loops). [S1]
- **Nested loops** — inner loop runs fully for each iteration of the outer loop. [S1]
- **`pass`** — required placeholder for an otherwise-empty for loop body. [S1]

## 🧩 추출된 패턴 (Extracted patterns)
- **break-before-vs-after-print changes output** — placing the `if x == "banana": break` check BEFORE the print vs. AFTER it changes whether "banana" itself gets printed before the loop exits — order within the loop body matters. [S1]

## 📖 세부 내용 (Details)
- Basic loop: `fruits = ["apple","banana","cherry"]; for x in fruits: print(x)`. [S1]
- range() exclusive end: `for x in range(6): print(x)` → prints 0,1,2,3,4,5. [S1]
- range() with start: `for x in range(2, 6):` → 2,3,4,5. [S1]
- range() with step: `for x in range(2, 30, 3):`. [S1]
- Nested loop: `for x in adj: for y in fruits: print(x, y)`. [S1]
- else on natural completion: `for x in range(6): print(x) else: print("Finally finished!")`. [S1]

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

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — 이후 List Comprehension 챕터에서 이 for 순회가 한 줄 표현식으로 압축된다. [S1]

## 💻 코드 패턴 (Code patterns)
range() with custom start/stop/step (Python):
```python
for x in range(2, 30, 3):
    print(x)
```
Nested loop over two lists (Python):
```python
adj = ["red", "big", "tasty"]
fruits = ["apple", "banana", "cherry"]
for x in adj:
    for y in fruits:
        print(x, y)
```

## ✅ 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 While Loops]], [[Python Lists Comprehension]], [[Python Range]]
- **참조 맥락:** Python 2대 반복문 중 하나 — List Comprehension으로 압축 가능한 순회 패턴.

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

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