文件夹，文件这是常见的，怎么创建？要不要先判断是否存在？非常非常基础的知识点。
代码
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO; namespace dazilianxi.wenjian
{
public class WenJianLei
{
const string main_Dir = @"D:/WenTest";
const string wenjianpath = @"D:\WenTest\second.txt";
//根据文件夹全路径创建文件夹
public static void CreateDir(string subdir)
{
string path = main_Dir + "/" + subdir;
if (Directory.Exists(path))
{
Console.WriteLine("此文件夹已经存在，无需创建！");
}
else
{
Directory.CreateDirectory(path);
Console.WriteLine(path+" 创建成功!");
}
}
//根据文件夹名称创建文件夹
public static void CreateNameDir(string name)
{
if(name.Length!=)
{
CreateDir(name);
}
else
{
Console.WriteLine("必须指定文件夹名称，才能创建！");
}
} public static void CreateWenJian()
{
if (!File.Exists(wenjianpath))
{
Console.WriteLine("文件创建成功！");
TextWriter tw = new StreamWriter(wenjianpath);
tw.WriteLine("创建完文件加的第一行~~");
tw.Close();
}
else
{
TextWriter tw = new StreamWriter(wenjianpath,true);
tw.WriteLine("已经存在文件，再加一行吧~~");
tw.Close();
}
}
//文件大小计算
public static void CreateMoreSize()
{
long size = GetDirectoryLength(@"D:\WenTest");
if (!File.Exists(wenjianpath))
{
if (size <= )
{
TextWriter tw = new StreamWriter(wenjianpath);
tw.WriteLine("创建完文件加的第一行~~");
tw.Close();
}
else
{
Console.WriteLine("无法创建，已经超过限定大小了~~");
} }
else
{
TextWriter tw = new StreamWriter(wenjianpath, true);
tw.WriteLine("已经存在文件，再加一行吧~~");
tw.Close();
}
}
public static long GetDirectoryLength(string path)
{
if (!Directory.Exists(path))
{
return ;
} long size = ; //遍历指定路径下的所有文件
DirectoryInfo di = new DirectoryInfo(path);
foreach (FileInfo fi in di.GetFiles())
{
size += fi.Length;
} //遍历指定路径下的所有文件夹
DirectoryInfo[] dis = di.GetDirectories();
if (dis.Length > )
{
for (int i = ; i < dis.Length; i++)
{
size += GetDirectoryLength(dis[i].FullName);
}
} return size;
}
}
}
调用代码
// wenjian.WenJianLei.CreateNameDir("mytest1");
//wenjian.WenJianLei.CreateWenJian();
wenjian.WenJianLei.CreateMoreSize();
来源：http://www.cnblogs.com/darrenji/p/3652062.html
http://www.cnblogs.com/hqbhonker/p/3494042.html