Best way to iterate folders and subfolders

Question

What's the best way to iterate folders and subfolders to get file size, total number of files, and total size of folder in each folder starting at a specified location?

Answer 1

Use Directory.GetFiles(). The bottom of that page includes an example that's fully recursive.

Note: Use Chris Dunaway's answer below for a more modern approach when using .NET 4 and above.

// For Directory.GetFiles and Directory.GetDirectories
// For File.Exists, Directory.Exists
using System;
using System.IO;
using System.Collections;

public class RecursiveFileProcessor 
{
    public static void Main(string[] args) 
    {
        foreach(string path in args) 
        {
            if(File.Exists(path)) 
            {
                // This path is a file
                ProcessFile(path); 
            }               
            else if(Directory.Exists(path)) 
            {
                // This path is a directory
                ProcessDirectory(path);
            }
            else 
            {
                Console.WriteLine("{0} is not a valid file or directory.", path);
            }        
        }        
    }

    // Process all files in the directory passed in, recurse on any directories 
    // that are found, and process the files they contain.
    public static void ProcessDirectory(string targetDirectory) 
    {
        // Process the list of files found in the directory.
        string [] fileEntries = Directory.GetFiles(targetDirectory);
        foreach(string fileName in fileEntries)
            ProcessFile(fileName);

        // Recurse into subdirectories of this directory.
        string [] subdirectoryEntries = Directory.GetDirectories(targetDirectory);
        foreach(string subdirectory in subdirectoryEntries)
            ProcessDirectory(subdirectory);
    }
    
    // Insert logic for processing found files here.
    public static void ProcessFile(string path) 
    {
        Console.WriteLine("Processed file '{0}'.", path);       
    }
}