When dealing with large directory structures, printing results to the console is not enough. Exporting the file tree to a CSV file allows you to analyze it in Excel, Power BI, or any reporting tool.

Exporting Directory and File Listings to CSV in C#

Step 1: Define the CSV Structure

A simple CSV format might include the following columns:

Type → Directory or File
Path → Full path of the item
Name → Only the file/folder name

Step 2: Recursive Function That Writes to CSV

We’ll extend the recursive function from Version 3 to save entries into a List<string> that will later be written to a .csv file.

using System;
using System.IO;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        string folderPath = @"C:\Test";
        string csvPath = @"C:\output.csv";

        var rows = new List<string>();
        rows.Add("Type,Path,Name"); // CSV header

        try
        {
            if (Directory.Exists(folderPath))
            {
                Console.WriteLine($"📂 Exporting recursive listing for: {folderPath}");
                ListDirectory(folderPath, rows);
                File.WriteAllLines(csvPath, rows);
                Console.WriteLine($"✅ Export completed. CSV saved at: {csvPath}");
            }
            else
            {
                Console.WriteLine("The specified folder does not exist.");
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"Error: {ex.Message}");
        }
    }

    static void ListDirectory(string path, List<string> rows)
    {
        try
        {
            // Add current directory
            rows.Add($"Directory,\"{path}\",\"{Path.GetFileName(path)}\"");

            // Add files
            foreach (var file in Directory.GetFiles(path))
            {
                rows.Add($"File,\"{file}\",\"{Path.GetFileName(file)}\"");
            }

            // Recurse into subdirectories
            foreach (var dir in Directory.GetDirectories(path))
            {
                ListDirectory(dir, rows);
            }
        }
        catch (UnauthorizedAccessException)
        {
            rows.Add($"Directory,\"{path}\",ACCESS DENIED");
        }
    }
}

Step 3: Example Output in CSV

If the folder contains:

C:\Test
 ┣ Project1
 ┃ ┗ data.csv
 ┣ Logs
 ┃ ┗ log1.txt
 ┗ readme.txt

The output.csv will look like:

Type,Path,Name
Directory,"C:\Test","Test"
File,"C:\Test\readme.txt","readme.txt"
Directory,"C:\Test\Project1","Project1"
File,"C:\Test\Project1\data.csv","data.csv"
Directory,"C:\Test\Logs","Logs"
File,"C:\Test\Logs\log1.txt","log1.txt"

Technical Summary

Step	Technique	Method
1	Store results in memory	`List<string>`
2	Add CSV header	`"Type,Path,Name"`
3	Write directories	`rows.Add("Directory,...")`
4	Write files	`rows.Add("File,...")`
5	Export to file	`File.WriteAllLines(csvPath, rows)`

✅ This approach gives you a clean CSV file of all directories and files, which can be directly opened in Excel or imported into data analysis tools.