---
id: php-variables
title: "PHP Variables"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["PHP 변수"]
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", "variables"]
raw_sources: ["https://www.w3schools.com/php/php_variables.asp"]
applied_in: []
github_commit: ""
---

# [[PHP Variables]]

## 🎯 한 줄 통찰 (One-line insight)
PHP has NO variable declaration command — a variable is created the instant you assign it a value (`$x = 5;`), unlike statically-declared languages; this is the source's explicit framing of what makes PHP "loosely typed" from the very first line of variable usage. [S1]

## 🧠 핵심 개념 (Core concepts)
- **`$` prefix** — every variable name starts with `$`. [S1]
- **Naming rules** — starts with a letter or underscore (never a number); alphanumeric + underscore only; case-sensitive. [S1]
- **No declaration keyword** — a variable springs into existence at first assignment. [S1]
- **Loosely typed** — PHP infers the data type from the assigned value; no explicit type annotation needed. [S1]
- **`var_dump()`** — reveals both the data type and value of a variable. [S1]
- **Multiple assignment** — `$x = $y = $z = "Fruit";` assigns the same value to several variables in one statement. [S1]
- **Supported data types** — string, int, float, bool, array, object, null, resource, mixed. [S1]

## 📖 세부 내용 (Details)
- Basic assignment: `$x = 5; $y = "John";`. [S1]
- Output with interpolation: `$txt = "W3Schools.com"; echo "I love $txt!";` — equivalent to `echo 'I love ' . $txt . '!';`. [S1]
- Type inspection: `var_dump(5); var_dump("John"); var_dump(3.14); var_dump(true); var_dump([2, 3, 56]); var_dump(NULL);`. [S1]
- Multi-assignment: `$x = $y = $z = "Fruit";`. [S1]

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

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — var_dump()로 변수의 실제 타입과 값을 확인하는 것이 디버깅의 표준 도구다. [S1]

## 💻 코드 패턴 (Code patterns)
Multi-variable assignment in one line (PHP):
```php
$x = $y = $z = "Fruit";
```

## ✅ 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 Variables Scope]], [[PHP Echo Print]], [[PHP Data Types]]
- **참조 맥락:** 변수 기초 문법 — 스코프(Scope)/데이터 타입 챕터로 확장.

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

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