---
id: php-callback-functions
title: "PHP Callback Functions"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["anonymous function callback", "PHP 콜백 함수"]
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: ["php", "programming", "w3schools", "callback", "functions"]
raw_sources: ["https://www.w3schools.com/php/php_callback_functions.asp"]
applied_in: []
github_commit: ""
---

# [[PHP Callback Functions]]

## 🎯 한 줄 통찰 (One-line insight)
A named function used as a callback is passed as a plain STRING ("myfunction"), not as a special function-reference syntax — meaning any existing function automatically qualifies as a callback with zero extra syntax, while anonymous functions are defined inline specifically for one-off, unnamed use cases. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Callback function** — a function passed as an argument into another function. [S1]
- **Named function callback** — pass the function's name as a string: `array_map("myfunction", $numbers)`. [S1]
- **Anonymous function callback** — defined inline: `array_map(function($n) {return($n * $n);}, $numbers)`. [S1]
- **Callbacks in user-defined functions** — a parameter holding a function is invoked by adding parentheses: `$format($str)`. [S1]

## 📖 세부 내용 (Details)
- Named function as callback: `function myfunction($n) { return($n * $n); } $numbers = [1, 2, 3, 4, 5]; print_r(array_map("myfunction", $numbers));`. [S1]
- Anonymous function as callback: `$res = array_map(function($n) {return($n * $n);}, $numbers);`. [S1]
- Callback passed to a user-defined function: `function printFormatted($str, $format) { echo $format($str); } printFormatted("Hello world", "exclaim"); printFormatted("Hello world", "ask");` (where `exclaim` and `ask` are separately-defined named functions). [S1]

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

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — array_map()에 콜백을 전달해 배열의 모든 요소를 변환하는 것이 함수형 스타일 배열 처리의 대표 사례다. [S1]

## 💻 코드 패턴 (Code patterns)
User-defined function accepting a callback (PHP):
```php
function exclaim($str) { return $str . "! "; }
function printFormatted($str, $format) {
    echo $format($str);
}
printFormatted("Hello world", "exclaim");
```

## ✅ 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:** [[PHP Tutorial]]
- **관련 개념:** [[PHP Filter Advanced]], [[PHP JSON]], [[PHP Arrays Functions]]
- **참조 맥락:** 함수를 인자로 전달하는 패턴 — JSON 챕터로 이어짐.

## 📚 출처 (Sources)
- [S1] W3Schools — PHP Callback Functions — https://www.w3schools.com/php/php_callback_functions.asp

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