.NETでフォルダーを比較する方法 – GroupDocsガイド

If you need to know how to compare folders in .NET, you’re in the right place. In this tutorial we’ll walk through using GroupDocs.Comparison to automatically detect differences between two directories, generate both TXT logs and rich HTML reports, and integrate the process into real‑world C# applications.

クイック回答

主な目的は何ですか？ To automate folder comparison and generate detailed TXT or HTML reports.
サポートされている出力形式は何ですか？ TXT for easy parsing and HTML to generate a visual report.
ライセンスは必要ですか？ A free trial works for learning; a commercial license removes watermarks for production.
Linux で実行できますか？ Yes – GroupDocs.Comparison supports .NET Core on Linux, macOS, and Windows.
対応している .NET バージョンは？ .NET Core 3.1+ and .NET 5/6/7/8.

このガイドで学べること

In this guide you will learn how to compare two directories in C# using GroupDocs.Comparison, generate both TXT and HTML reports, handle large folder structures efficiently, and integrate the comparison into CI/CD pipelines or backup verification scripts. You’ll also discover how to tune performance for massive data sets and customize the HTML report layout for your needs.

.NET開発者にとってフォルダー比較が重要な理由

Folder comparison saves you from manually scanning hundreds of files. Whether you’re validating deployments, checking backups, or tracking configuration drift, compare directories C# style lets you spot added, removed, or modified files in seconds instead of hours.

前提条件と環境設定

Before we jump into the fun stuff, let’s make sure you have everything you need. Don’t worry – the setup is straightforward, and I’ll walk you through each step.

必要なもの

必要なライブラリとバージョン

GroupDocs.Comparison for .NET: Version 25.4.0 (the latest stable release as of 2025) – supports 50+ input and output formats including DOCX, PDF, HTML, and image types.
.NET Framework/SDK: Compatible with .NET Core 3.1+ and .NET 5/6/7/8
Development Environment: Visual Studio 2019+ (Community edition works perfectly)

前提知識

Basic understanding of C# programming (if you can write a simple console app, you’re good to go)
Familiarity with file system operations in .NET (working with paths, directories, files)
Understanding of NuGet package management

クイック環境チェック

Open your preferred IDE (Visual Studio, VS Code, or JetBrains Rider)
Create a new console application targeting .NET Core 3.1 or later
Ensure you can access NuGet Package Manager

If you can do these three things, you’re all set! Now let’s get GroupDocs.Comparison installed and configured.

GroupDocs.Comparisonのインストールと設定

Getting GroupDocs.Comparison up and running in your project is a breeze. You have two main installation methods, and I’ll show you both.

インストール方法

オプション1: NuGet パッケージマネージャコンソール (Visual Studio ユーザーに推奨)

Install-Package GroupDocs.Comparison -Version 25.4.0

オプション2: .NET CLI (コマンドライン愛好者に最適)

dotnet add package GroupDocs.Comparison --version 25.4.0

Pro tip: Always specify the version to ensure consistency across your team and deployment environments.

ライセンスオプションの理解

GroupDocs.Comparison offers flexible licensing that fits different needs:

Free Trial: Perfect for evaluation – gives you access to all features with some limitations
Temporary License: Ideal for proof‑of‑concept projects – removes trial restrictions temporarily
Commercial License: Full features for production applications

For learning purposes, the free trial is more than sufficient. You can always upgrade later when you’re ready to deploy.

基本的な初期化と設定

Here’s your first piece of GroupDocs.Comparison code. This simple setup verifies everything is working correctly:

using System;
using GroupDocs.Comparison;

class Program
{
    static void Main()
    {
        // Initialize the license if available
        License license = new License();
        // license.SetLicense("Path to your license file"); // Uncomment when you have a license

        Console.WriteLine("GroupDocs.Comparison for .NET is ready to use.");
        Console.WriteLine("Let's start comparing some folders!");
    }
}

If this code runs without errors, congratulations! You’re ready to start building powerful folder comparison functionality.

フォルダーを比較し、結果をTXTファイルとして保存する方法

Let’s start with the most straightforward approach: comparing two directories and saving the results as a text file. This method is perfect for automated scripts, logging systems, or when you need a simple, parseable output format.

TXT出力を選ぶ理由

Text files are incredibly versatile. They’re lightweight, easy to parse programmatically, version‑control friendly, and can be viewed on any system. Perfect for:

Automated build processes → 自動ビルドプロセス
Log file analysis → ログファイル解析
Command‑line tools → コマンドラインツール
Integration with other systems → 他システムとの統合

ステップバイステップ実装

The FolderComparisonOptions class lets you fine‑tune the comparison.
Definition anchor: FolderComparisonOptions defines all configurable settings for a folder comparison operation.

using System;
using System.IO;
using GroupDocs.Comparison;
using GroupDocs.Comparison.Options;

string sourceFolder = "YOUR_DOCUMENT_DIRECTORY/SOURCE_FOLDER";
string targetFolder = "YOUR_DOCUMENT_DIRECTORY/TARGET_FOLDER";
string outputDirectory = "YOUR_OUTPUT_DIRECTORY";

// Set comparison options for TXT output
Options.CompareOptions compareOptionsTxt = new Options.CompareOptions
{
    DirectoryCompare = true,
    FolderComparisonExtension = GroupDocs.Comparison.Options.FolderComparisonExtension.Txt
};

You’re telling GroupDocs.Comparison that you want to compare entire directories (not individual files) and output the results in text format. The DirectoryCompare = true setting is crucial—it enables the recursive directory comparison functionality.

ステップ1: 比較オプションの設定

Definition anchor: FolderComparisonOptions defines all configurable settings for a folder comparison operation.

ステップ2: Comparerオブジェクトの初期化

Definition anchor: Comparer is the core class that performs the comparison between source and target items.

Comparer comparerTxt = new Comparer(sourceFolder, compareOptionsTxt);
// Add target folder for comparison
comparerTxt.Add(targetFolder, compareOptionsTxt);

This is where the magic begins. You’re creating a Comparer instance with your source folder as the baseline, then adding the target folder for comparison. Think of it like saying “compare everything in folder B against folder A.”

ステップ3: 比較を実行し、結果を保存

string txtOutputFileName = Path.Combine(outputDirectory, "ComparisonResult.txt");
comparerTxt.Compare(txtOutputFileName, compareOptionsTxt);

Console.WriteLine("TXT file with comparison results saved successfully.");
Console.WriteLine($"Check your results at: {txtOutputFileName}");

That’s it! Your comparison results are now saved as a text file. The output will include details about added, deleted, and modified files, making it easy to understand what changed between the two directories.

TXT出力形式の理解

The generated text file typically includes:

Added files – present in the target but not in the source → 追加されたファイル – ターゲットに存在し、ソースに存在しないもの
Deleted files – present in the source but not in the target → 削除されたファイル – ソースに存在し、ターゲットに存在しないもの
Modified files – exist in both directories but have different content → 変更されたファイル – 両ディレクトリに存在するが内容が異なるもの
File metadata – size, modification dates, and other relevant information → ファイルメタデータ – サイズ、更新日時、その他の関連情報

フォルダーを比較し、結果をHTMLファイルとして保存する方法

While TXT files are great for automation, HTML output shines when you need a visual, human‑readable report. HTML comparison results are perfect for code reviews, client presentations, or when you want to share findings with non‑technical team members.

HTML出力の利点（およびHTMLレポートの生成方法）

Visual diff highlighting – see exactly what changed with color‑coded differences → ビジュアル差分ハイライト – 色分けされた差分で正確に変更点を確認
Interactive navigation – click through files and folders easily → インタラクティブなナビゲーション – ファイルやフォルダーをクリックで簡単に移動
Professional presentation – ideal for reports and documentation → プロフェッショナルな提示 – レポートやドキュメントに最適
Cross‑platform viewing – opens in any web browser → クロスプラットフォーム閲覧 – 任意のウェブブラウザで開くことが可能

ステップ1: HTML比較オプションの設定

Definition anchor: FolderComparisonExtension.Html tells the API to produce an HTML‑based report instead of plain text.

// Set comparison options for HTML output
Options.CompareOptions compareOptionsHtml = new Options.CompareOptions
{
    DirectoryCompare = true,
    FolderComparisonExtension = GroupDocs.Comparison.Options.FolderComparisonExtension.Html
};

The key difference here is the FolderComparisonExtension.Html setting. This tells GroupDocs.Comparison to generate a rich HTML report instead of plain text.

ステップ2: HTML出力用Comparerの初期化

Comparer comparerHtml = new Comparer(sourceFolder, compareOptionsHtml);
// Add target folder to the comparison
comparerHtml.Add(targetFolder, compareOptionsHtml);

Same pattern as before, but now configured for HTML output. The beauty of GroupDocs.Comparison’s API is its consistency—you use the same methods regardless of output format.

ステップ3: HTMLレポートの生成と保存

string htmlOutputFileName = Path.Combine(outputDirectory, "ComparisonResult.html");
comparerHtml.Compare(htmlOutputFileName, compareOptionsHtml);

Console.WriteLine("HTML file with comparison results saved successfully.");
Console.WriteLine($"Open in browser: {htmlOutputFileName}");

The HTML file you get is a complete, self‑contained report that you can open in any web browser. It includes interactive elements, syntax highlighting (for code files), and a clean, professional layout.

HTMLレポートで期待できること

Your HTML output will typically include:

Summary dashboard – overview of total changes, files affected, and comparison statistics → サマリーダッシュボード – 変更総数、影響を受けたファイル、比較統計の概要
Side‑by‑side comparisons – visual diff view showing exactly what changed → サイドバイサイド比較 – 変更点を視覚的に示す差分ビュー
Folder tree navigation – easy browsing through the directory structure → フォルダーツリーナビゲーション – ディレクトリ構造を簡単に閲覧
File‑level details – individual file comparisons with highlighted differences → ファイルレベルの詳細 – ハイライトされた差分付きの個別ファイル比較

一般的なユースケースと実際のアプリケーション

Understanding when and how to use folder comparison can significantly improve your development workflow. Here are some scenarios where this functionality proves invaluable:

コードレビューとバージョン管理

シナリオ: You’re reviewing changes between two branches or comparing different versions of your codebase.

フォルダー比較が有効な理由: Instead of checking files one by one, you can instantly see all modifications, additions, and deletions across your entire project structure. The HTML output is particularly useful here—you can share visual diff reports with your team.

データバックアップの検証

シナリオ: You need to verify that your backup process correctly copied all files and that no corruption occurred.

実装のヒント: Use TXT output for automated verification scripts that can be integrated into your backup workflow. Set up alerts when discrepancies are detected.

環境間の構成管理

シナリオ: You’re managing application configurations across development, staging, and production environments.

ベストプラクティス: Regular folder comparisons help catch configuration drift before it causes production issues. HTML reports are perfect for change‑management documentation.

ドキュメントバージョン管理

シナリオ: You’re managing document repositories where multiple team members make changes to files.

プロのコツ: Combine folder comparison with scheduled tasks to automatically generate change reports. This is especially useful for compliance and audit purposes.

CI/CDパイプライン統合

シナリオ: You want to automatically detect and report changes as part of your deployment process.

高度な使用例: Integrate folder comparison into your build pipeline to generate change reports for each deployment, helping with rollback decisions and change tracking.

パフォーマンス最適化とベストプラクティス

When working with large directory structures, performance becomes crucial. Here are proven strategies to keep your folder comparisons running smoothly:

最適化戦略

スマートディレクトリ選択
- Compare only the directories you actually need to analyze
- Use filters to exclude temporary files, logs, or other irrelevant content
- Consider splitting very large comparisons into smaller, focused chunks
Memory Management

Definition anchor: Comparer.Dispose() releases all unmanaged resources held by the comparer, preventing memory leaks.

// Dispose of comparer objects properly
using (Comparer comparer = new Comparer(sourceFolder, compareOptions))
{
    comparer.Add(targetFolder, compareOptions);
    comparer.Compare(outputFileName, compareOptions);
} // Automatically disposed here

Asynchronous Processing
For large comparisons, consider implementing async patterns to prevent UI blocking in desktop applications or timeout issues in web applications.

パフォーマンス監視のヒント

Monitor memory usage during large comparisons → 大規模比較時のメモリ使用量を監視
Track processing time for different directory sizes → ディレクトリサイズ別の処理時間を追跡
Set realistic expectations for users based on directory complexity → ディレクトリの複雑さに基づき、ユーザーに現実的な期待値を設定
Consider progress reporting for long‑running operations → 長時間実行される操作には進捗報告を検討

一般的な問題のトラブルシューティング

Even with well‑written code, you might encounter some challenges. Here are the most common issues and their solutions:

File Access and Permission Issues

Problem: “Access denied” or “file in use” errors

Solution:

Ensure your application runs with appropriate permissions
Check that files aren’t locked by other processes
Implement retry logic for temporary file locks

Path and Directory Issues

Problem: Invalid path errors or directory not found

Solution:

// Always validate paths before comparison
if (!Directory.Exists(sourceFolder))
{
    throw new DirectoryNotFoundException($"Source directory not found: {sourceFolder}");
}

if (!Directory.Exists(targetFolder))
{
    throw new DirectoryNotFoundException($"Target directory not found: {targetFolder}");
}

Memory and Performance Issues

Problem: Out of memory exceptions or slow performance

Solutions:

Break large comparisons into smaller batches
Exclude unnecessary file types from comparison
Monitor and optimize memory usage patterns

Output File Generation Issues

Problem: Output files not generated or corrupted

Troubleshooting steps:

Verify write permissions in the output directory
Ensure sufficient disk space
Check for invalid characters in file paths
Validate output directory exists before comparison

高度な構成オプション

GroupDocs.Comparison offers numerous configuration options that let you fine‑tune comparison behavior:

Comparison Sensitivity Settings

You can adjust how sensitive the comparison is to different types of changes:

Whitespace handling – ignore or include whitespace changes → 空白の取り扱い – 空白の変更を無視または含める
Case sensitivity – control whether case differences are considered changes → 大文字小文字の感度 – 大文字小文字の違いを変更とみなすか制御
Line ending normalization – handle different line ending formats → 改行コードの正規化 – 異なる改行形式を処理

File Type Filtering

Focus your comparisons on specific file types:

compareOptions.FileAuthorMetadata = false; // Ignore metadata changes
compareOptions.GenerateFramePreview = true; // Generate preview frames

Custom Output Formatting

Tailor the output format to your specific needs:

Custom templates – modify HTML output styling → カスタムテンプレート – HTML 出力のスタイルを変更
Metadata inclusion – control what file information is included → メタデータの含有 – 含めるファイル情報を制御
Diff granularity – choose between file‑level or line‑level comparisons → 差分粒度 – ファイルレベルまたは行レベルの比較を選択

結論と次のステップ

Congratulations! You’ve mastered the fundamentals of folder comparison using GroupDocs.Comparison for .NET. You now have the skills to:

✅ プロジェクトで GroupDocs.Comparison をセットアップおよび構成
✅ ディレクトリを比較し、TXT と HTML の両方のレポートを生成（HTML レポートの生成 方法を含む）
✅ 一般的な課題に対処し、パフォーマンスを最適化
✅ フォルダー比較を実際のアプリケーションに統合

次は何ですか？

Ready to take your folder comparison skills to the next level? Consider exploring:

高度なフィルタリングオプション – よりターゲットを絞った比較
API 統合 – Web ベースの比較サービス向け
バッチ処理 – 複数のディレクトリペアの処理
カスタムレポート形式 – 組織のニーズに合わせたレポート

今日から実装を開始

The best way to master these concepts is through hands‑on practice. Pick one of your current projects and identify where folder comparison could streamline your workflow. Start small, experiment with different output formats, and gradually incorporate more advanced features.

Remember: every expert was once a beginner. Take your time, experiment freely, and don’t hesitate to reference this guide whenever you need a refresher!

よくある質問

Q: Linux システムで .NET 用 GroupDocs.Comparison を使用できますか？
A: Absolutely! GroupDocs.Comparison fully supports cross‑platform deployment through .NET Core. It works seamlessly on Linux, macOS, and Windows environments.

Q: 数千ファイルの非常に大きなディレクトリはどう扱うべきですか？
A: For large directories, implement these strategies: use asynchronous processing, break comparisons into smaller batches, exclude unnecessary file types, and monitor memory usage. Consider providing progress feedback to users for long‑running operations.

Q: 比較できるファイル数に実質的な上限はありますか？
A: While there’s no hard limit built into the library, performance depends on your system resources (RAM, CPU, disk speed) and file sizes. Most systems can handle thousands of files without issues, but very large datasets might require optimisation strategies.

Q: GroupDocs.Comparison は暗号化またはパスワード保護されたファイルを扱えますか？
A: The library cannot directly compare encrypted files. You’ll need to decrypt files first if you have the appropriate permissions and credentials. Always ensure you comply with your organisation’s security policies when handling encrypted content.

Q: フォルダー比較を自動化された CI/CD パイプラインに統合するには？
A: Create console applications that use GroupDocs.Comparison, configure them to return appropriate exit codes based on comparison results, and integrate them into your build scripts. TXT output is particularly useful for parsing results in automated environments.

Q: トライアル版とライセンス版の違いは何ですか？
A: The trial version includes all functionality but adds watermarks to output and has some usage limitations. Licensed versions remove these restrictions and are suitable for production use.

Q: HTML 出力のスタイルやレイアウトをカスタマイズできますか？
A: Yes, GroupDocs.Comparison provides options to customize HTML output. You can modify templates, adjust styling, and control what information is included in the reports.

Q: 片方のディレクトリにしか存在しないファイルはどう扱いますか？
A: GroupDocs.Comparison automatically identifies and reports these differences as “added” or “deleted” files. You can configure how these differences are presented in your output format.

追加リソースとサポート

ドキュメンテーション

Complete API Reference: GroupDocs.Comparison .NET API Documentation
Developer Guide: GroupDocs Developer Resources

ダウンロードとライセンス

最新リリース: Download GroupDocs.Comparison
購入オプション: Buy Commercial License
無料トライアル: Start Your Free Trial
一時ライセンス: Request Evaluation License

Last Updated: 2026-07-20
Tested With: GroupDocs.Comparison 25.4.0 for .NET
Author: GroupDocs