(C#基础)创建文件，文件夹

    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:WenTestsecond.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!=0)
            {
                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 <= 1)
                {
                    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 0;
            }

            long size = 0;

            //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 > 0)
            {
                for (int i = 0; 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