[取得指定往下第幾層的資料夾路徑] 只取指定層數的資料夾路徑，避免子資料夾路徑太深、太多造成效能問題 #dotnet

EnumerateSubDirectories.cs

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

/// <summary>
/// 取得指定往下第幾層的資料夾路徑
/// </summary>
/// <remarks>使用此方法只取指定層數的資料夾路徑，避免子資料夾路徑太深、太多造成效能問題</remarks>
/// <param name="path">根路徑</param>
/// <param name="depth">第幾層的資料夾路徑</param>
/// <returns></returns>
public static IEnumerable<string> EnumerateSubDirectories(string path, int depth)
{
    if (!Directory.Exists(path)) return new List<string>();

    var result = new List<string>();
    depth--;

    foreach (var subPath in Directory.EnumerateDirectories(path, "*", SearchOption.TopDirectoryOnly))
    {
        result.AddRange(depth == 0 ? new List<string> { subPath } : EnumerateSubDirectories(subPath, depth));
    }

    return result;
}