C#搜索文字在文件及文件夹中出现位置的方法

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace Search
{
 class Program
 {
 static void Main(string[] args)
 {
  if (args.Length != 3 || (args[0] != "file" && args[0] != "folder"))
  {
  Console.WriteLine("Correct Order Style: ");
  Console.WriteLine("Search file/folder address word");
  }
  switch (args[0])
  {
  case "file": //从文件中查找
   {
   if (System.IO.File.Exists(args[1]))
   {
    FindInFile(args[1], args[2]);
   }
   else
   {
    Console.WriteLine(string.Format(
    "File {0} not exist!", args[1]));
   }
   }
   break;
  case "folder": //从文件夹中查找（包括其中全部文件）
   {
   if (System.IO.Directory.Exists(args[1]))
   {
    FindInDirectory(args[1], args[2]);
   }
   else
   {
    Console.WriteLine(string.Format(
    "Directory {0} not exist!", args[1]));
   }
   }
   break;
  default: break;
  }
  Console.WriteLine("Output Finished.");
  Console.ReadLine();
 }
 /// <summary>
 /// 从文件中找关键字
 /// </summary>
 /// <param name="filename"></param>
 /// <param name="word"></param>
 public static void FindInFile(string filename, string word)
 {
  System.IO.StreamReader sr = System.IO.File.OpenText(filename);
  string s = sr.ReadToEnd();
  sr.Close();
  string[] temp = s.Split('\n');
  for (int i = 0; i < temp.Length; i++)
  {
  if (temp[i].IndexOf(word) != -1)
  {
   Console.WriteLine(string.Format(
   "Found in: {0}\n{1}\nLine: {2} \n",
   filename, temp[i].Trim(), i + 1));
  }
  }
 }
 /// <summary>
 /// 从文件夹中找关键字
 /// </summary>
 /// <param name="foldername"></param>
 /// <param name="word"></param>
 public static void FindInDirectory(string foldername, string word)
 {
  System.IO.DirectoryInfo dif = new System.IO.DirectoryInfo(foldername);
  //遍历文件夹中的各子文件夹
  foreach (System.IO.DirectoryInfo di in dif.GetDirectories())
  {
  FindInDirectory(di.FullName, word);
  }
  //查询文件夹中的各个文件
  foreach (System.IO.FileInfo f in dif.GetFiles())
  {
  FindInFile(f.FullName, word);
  }
 }
 }
}