2nd/10_Wiki/Dev/Topic_C/C_Do_While_Loop.md

id, title, category, status, verification_status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, created_at, updated_at, review_reason, merge_history, tags, raw_sources, applied_in, github_commit

id	title	category	status	verification_status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	created_at	updated_at	review_reason	merge_history	tags	raw_sources	applied_in	github_commit
c-do-while-loop	C Do/While Loop	Programming_Language	draft	conceptual		do while at-least-once loop scanf input validation loop C do-while 반복문		B	0.86	2026-07-04	2026-07-04			c programming-language w3schools loops do-while	https://www.w3schools.com/c/c_do_while_loop.php

C Do/While Loop

🎯 한 줄 통찰 (One-line insight)

The core difference from a regular while loop isn't cosmetic syntax — it's WHEN the condition is checked: do/while runs the body FIRST and evaluates the condition only AFTER, guaranteeing at least one execution even if the condition is false from the very start (int i = 10; do {...} while (i < 5); still runs once), which is exactly the opposite of the plain while loop's zero-iteration behavior shown in the previous chapter. [S1]

🧠 핵심 개념 (Core concepts)

• do { ... } while (condition); — executes the block ONCE unconditionally, then checks the condition to decide whether to repeat. [S1]
• Guaranteed first execution — unlike while, the body runs at least once even if the condition is false immediately. [S1]
• Use case: "at least once" behavior — ideal for scenarios like showing a message or prompting for user input, where the action must happen before any condition can even be evaluated. [S1]
• Input-validation pattern — repeatedly prompting via scanf() until the user provides a value that fails the loop condition (e.g. entering 0 or negative to stop). [S1]

📖 세부 내용 (Details)

• Standard case (condition true at start): int i = 0; do { printf("%d\n", i); i++; } while (i < 5);. [S1]
• Guaranteed-once case (condition false at start): int i = 10; do { printf("i is %d\n", i); i++; } while (i < 5); — still prints once despite i < 5 being false immediately. [S1]
• Practical input-validation loop: int number; do { printf("Enter a positive number: "); scanf("%d", &number); } while (number > 0); — keeps prompting until 0 or a negative number is entered. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

• do/while은 조건과 무관하게 최소 1회 실행: 일반 while 루프는 조건이 처음부터 거짓이면 아예 실행되지 않지만, do/while은 조건이 거짓이어도 반드시 한 번은 실행된다는 점이 직접 대비되어 강조됨. [S1]

🛠️ 적용 사례 (Applied in summary)

사용자로부터 양수를 입력받되 0이나 음수가 입력될 때까지 반복해서 물어보는 입력 검증 루프가 원문에서 직접 실전 활용 사례로 제시됨. [S1]

💻 코드 패턴 (Code patterns)

An input-validation loop that must prompt at least once before checking the exit condition (C):

int number;
do {
  printf("Enter a positive number: ");
  scanf("%d", &number);
} while (number > 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 While Loop RealLife, C For Loop, C User Input
• 참조 맥락: while 루프의 변형 — for 루프(For Loop) 챕터로 이어짐, 사용자 입력(User Input) 챕터와 연결.

📚 출처 (Sources)

• [S1] W3Schools — C Do/While Loop — https://www.w3schools.com/c/c_do_while_loop.php

📝 변경 이력 (Change history)

• 2026-07-04: Initial draft synthesized from the W3Schools "C Do/While Loop" page (Astra wiki-curation, P-Reinforce v3.1 format).