获取目标路径下所有文件名的枚举集合

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Diagnostics;
using System.IO;

namespace Csharp
{
class Program
{
static IEnumerable GetAllFiledInDirectory(string directoryPath)
{
IEnumerable files          = null;
IEnumerable subDirectories = null;
try {
files          = Directory.EnumerateFiles(directoryPath);
subDirectories = Directory.EnumerateDirectories(directoryPath);
}
catch (UnauthorizedAccessException) {
Console.WriteLine("Cannot get permission to access " + directoryPath);
}

if (files != null)
foreach (var file in files)
yield return file;
if (subDirectories != null)
foreach (var subdirectory in subDirectories)
foreach (var file in GetAllFiledInDirectory(subdirectory))
yield return file;
}
static void Main(string[] args)
{
var files = GetAllFiledInDirectory(@"d:\");
int i = 0;
foreach (var file in files) {
Console.WriteLine(file);
if (i++ == 100) break;
}
}
}
}