11-git-diff.md

🔎 git diff (See Changes)

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🎯 What It Does

Shows differences between versions.

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🧪 Command

git diff

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📸 Visual (Diff Comparison)

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🧠 Mental Model

git diff = compare snapshots

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🏗 Internal Architecture

Git compares:

Working Directory ↔ Index ↔ HEAD

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🔬 Diff Types

1. Working vs Staging

git diff

2. Staging vs Last Commit

git diff --staged

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🧩 Example

Before:

Hello

After:

Hello World

Diff:

+ World

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🧠 How Git Computes Diff

Git uses algorithms (like Myers diff) to:

• find added lines
• find removed lines
• show minimal changes

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⚠️ Common Mistake

Not checking diff before commit.

👉 Leads to wrong commits

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🧠 Why This Matters

Because:

• helps debugging
• shows exact changes
• prevents mistakes

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🧠 Memory Trick

diff = what changed

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➡️ Next Step

👉 12-ignore-files.md