Git Diff to Compare Changes

Git Diff to Compare Changes

Git diff is a powerful command for comparing changes in your repository. This guide will show you how to use Git diff effectively to review code changes, track modifications, and understand differences between versions.

What You’ll Learn

• Basic Git diff commands
• Different diff formats and options
• How to compare specific changes
• Visualizing differences
• Best practices for code review

Implementation Steps

1. Basic Diff Command

   # Show unstaged changes
   git diff
   

   • Shows changes in working directory
   • Compares with staged changes
   • Displays line-by-line differences
   • Uses +/- to show additions/deletions

2. Staged Changes

   # Show staged changes
   git diff --staged
   

   • Shows changes ready to commit
   • Compares with last commit
   • Good for review before commit
   • Helps catch mistakes

3. Compare Commits

   # Compare two commits
   git diff commit1 commit2
   
   # Compare with previous commit
   git diff HEAD~1
   

   • Shows changes between commits
   • Useful for code review
   • Helps track feature changes
   • Good for release notes

4. Compare Branches

   # Compare branches
   git diff main..feature
   
   # Compare with remote
   git diff origin/main
   

   • Shows branch differences
   • Helps with merge planning
   • Good for feature review
   • Useful for conflict resolution

Best Practices

1. Diff Formatting

   • Use --color-words for word-level changes
   • Use --stat for summary
   • Use --name-only for file list
   • Use --name-status for file status

2. Code Review

   • Review changes before committing
   • Check for unintended changes
   • Look for sensitive data
   • Verify formatting

3. Diff Tools

   # Configure external diff tool
   git config --global diff.tool vscode
   git config --global difftool.vscode.cmd 'code --wait --diff $LOCAL $REMOTE'
   

4. Diff Documentation

   • Document significant changes
   • Explain complex diffs
   • Reference issue numbers
   • Keep diffs focused

Common Use Cases

1. Reviewing Changes

   # Show word-level changes
   git diff --color-words
   
   # Show file statistics
   git diff --stat
   

2. Comparing Files

   # Compare specific files
   git diff file1.txt file2.txt
   
   # Compare file versions
   git diff HEAD~1:file.txt file.txt
   

3. Checking Staged Changes

   # Show staged changes
   git diff --staged
   
   # Show staged file list
   git diff --staged --name-only
   

4. Branch Comparison

   # Show branch differences
   git diff main...feature
   
   # Show file changes
   git diff main...feature -- file.txt
   

Advanced Usage

1. Custom Diff Format

   # Show context lines
   git diff -U5
   
   # Show function context
   git diff -W
   

2. Diff with Blame

   # Show who changed each line
   git blame file.txt
   
   # Show commit info
   git log -p file.txt
   

3. Diff with Patches

   # Create patch file
   git diff > changes.patch
   
   # Apply patch
   git apply changes.patch
   

4. Diff with Reflog

   # Show all changes
   git diff HEAD@{1}
   
   # Show branch changes
   git diff HEAD@{1}...HEAD
   

Common Issues and Solutions

1. Large Diffs

   # Show only file names
   git diff --name-only
   
   # Show only changed lines
   git diff --unified=0
   

2. Binary Files

   # Show binary file changes
   git diff --text
   
   # Ignore binary files
   git diff --diff-filter=AM
   

3. Whitespace Changes

   # Ignore whitespace
   git diff -w
   
   # Show only whitespace
   git diff --check
   

Conclusion

Git diff is an essential tool for code review and change tracking. Remember to:

• Use appropriate diff formats
• Review changes carefully
• Document significant changes
• Keep diffs focused
• Use diff tools effectively

Next Steps

After mastering Git diff, you might want to:

• Learn about Git merge
• Explore Git rebase
• Study Git hooks
• Understand Git internals