一个C# 文件操作的问题，我菜鸟一个，求指教！

Question

   我想知道，如何使用FileStream,StreamReader,StreamWriter这种方式来打开一个TXT文件，当然文件事先有内容格式如下：
   精舞门 罗志祥
   漂移 周杰伦
   四面楚歌 周杰伦
我想要打开这个文件，然后把某一行删除掉，再把删除后的结果写会源文件，求指教！

Answer 1

List<string> lst=List<String>(File.ReadAllLines(""));
var l=from s in lst where !s.Contains("") select s;
File.WriteAllText("");StreamReader sr = new StreamReader(@"E:\test.txt");
            String content = sr.ReadToEnd();
            sr.Close();
            String[] ss = content.Split(new char[]{'\n','\r'},StringSplitOptions.RemoveEmptyEntries);
            StreamWriter sw = new StreamWriter(@"E:\test.txt");
            for (Int32 i = 0; i < ss.Length; i++)
            {
                sw.WriteLine(ss[i].Trim('/'));
            }            sw.Close();

Answer 2

楼主应该明白了，但是鉴于楼主是新手可能对ling不熟悉，所以你可以把var 1换掉

Answer 3

   private void test()
        {
            string filePath = "f:\\my.txt";
            StreamReader sr = new StreamReader(filePath);
            string line = "";
            while ((line = sr.ReadLine()) != null)
            {
                //读取要修改的行内容
                if (line == "the content of del")
                    break;
            }
            sr.Close();            //写入新内容
            File.AppendAllText(filePath, "the new content");
        }
//刚好在code咯，就给你写了一小段

Answer 4

没，我对数据库最感兴趣了，最先就是学的LinQ

Answer 5

1. ReadAllLines
2. for each 或者 linq 过滤
3. WriteAllLines

Answer 6

还没搞定？
给你写了个帖子，你看看吧
源码：using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.IO;namespace testfilestream
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }        private int numoflines=0;
        private string ofd_filepath = string.Empty;
        List<string> list = new List<string>();
        private void 打开ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            OpenFileDialog ofd = new OpenFileDialog();
            ofd.Filter = "文本文件(*.txt)|*.txt";
            ofd.Title = "打开文本文件";
            ofd.Multiselect = false;
            if (ofd.ShowDialog() == DialogResult.OK)
            {
                ofd_filepath = Path.GetFullPath(ofd.FileName);
                readtext(ofd.FileName);
                list_bind_richtextbox();
            }
        }        private void readtext(string filename)
        {
            richTextBox1.Text = string.Empty;
            using (StreamReader sr = new StreamReader(filename, Encoding.Default))
            {
                while (sr.Peek() > -1)
                {
                    list.Add(sr.ReadLine());
                }
                numoflines = list.Count;
                sr.Close();
            }
        }
        private void list_bind_richtextbox()
        {
            richTextBox1.Text = "";
            for (int i = 0; i < list.Count; i++)
            {
                richTextBox1.Text += list[i].ToString() + "\r\n";
            }
        }        private void button1_Click(object sender, EventArgs e)
        {
            if (textBox1.Text.Length < 1)
            {
                MessageBox.Show("请输入想跳至的行");
            }
            else if (int.Parse(textBox1.Text) > numoflines)
            {
                MessageBox.Show("错误！你输入的行数大于文本框现有的行数");
            }
            else
            {
                richTextBox1.SelectionStart = richTextBox1.GetFirstCharIndexFromLine(int.Parse(textBox1.Text) - 1);
                richTextBox1.SelectionLength = 0;
                richTextBox1.Focus();
                richTextBox1.ScrollToCaret();                if (MessageBox.Show("你确定要删除该行数据吗？") == DialogResult.OK)
                {
                    list.RemoveAt(int.Parse(textBox1.Text)-1);
                    list_bind_richtextbox();
                }
            }         }        private void 保存ToolStripMenuItem_Click(object sender, EventArgs e)
        {
            try
            {
                FileStream fs = new FileStream(ofd_filepath, FileMode.OpenOrCreate, FileAccess.Write);
                StreamWriter sw = new StreamWriter(fs, Encoding.Default);
                sw.Flush();
                // 使用StreamWriter来往文件中写入内容
                sw.BaseStream.Seek(0, SeekOrigin.Begin);
                for (int i = 0; i < list.Count; i++) sw.WriteLine(list[i]);
                //关闭此文件t
                sw.Flush();
                sw.Close();
                fs.Close();
                MessageBox.Show("保存成功！");
            }
            catch (Exception ex)
            {
                MessageBox.Show("保存失败！错误信息："+ex.ToString());
            }
        }
    }
}

Answer 7

呵呵，1楼的代码好像确实有问题，因为程序报错了，出现了IO异常，我的完整代码是：
//简单地从从所有播放列表中搜索目标歌曲，并删除
        private void deleteSongs(String song)
        {
            for (int i = 0; i < PlayLists.Items.Count; i++)
            {
                int index = Convert.ToInt32(PlayLists.Items[i].ToString().Substring(4));
                fileURL = @"F:\我们的歌\播放列表" + index.ToString() + ".txt";                String record;
                FileStream fs = null;
                StreamReader sr = null;
                StreamWriter sw = null;
                FileInfo fi = new FileInfo(fileURL);
                try
                {
                    fs = new FileStream(fileURL, FileMode.OpenOrCreate, FileAccess.ReadWrite);
                    sr = new StreamReader(fs);
                    sw = new StreamWriter(fs);                    record = sr.ReadLine();
                    while (record != null)
                    {
                        String[] s = null;
                        Char[] spliter = new Char[] { ' ' };
                        s = record.Split(spliter);                        switch (index)
                        {
                            case 1:
                                deleteSong(fs, sw, sr, s, spliter, record, fileURL, song, recordArray1);
                                break;
                            case 2:
                                deleteSong(fs, sw, sr, s, spliter, record, fileURL, song, recordArray2);
                                break;
                            case 3:
                                deleteSong(fs, sw, sr, s, spliter, record, fileURL, song, recordArray3);
                                break;
                            case 4:
                                deleteSong(fs, sw, sr, s, spliter, record, fileURL, song, recordArray4);
                                break;
                            case 5:
                                deleteSong(fs, sw, sr, s, spliter, record, fileURL, song, recordArray5);
                                break;
                            case 6:
                                deleteSong(fs, sw, sr, s, spliter, record, fileURL, song, recordArray6);
                                break;
                            case 7:
                                deleteSong(fs, sw, sr, s, spliter, record, fileURL, song, recordArray7);
                                break;
                            case 8:
                                deleteSong(fs, sw, sr, s, spliter, record, fileURL, song, recordArray8);
                                break;
                            case 9:
                                deleteSong(fs, sw, sr, s, spliter, record, fileURL, song, recordArray9);
                                break;
                            case 10:
                                deleteSong(fs, sw, sr, s, spliter, record, fileURL, song, recordArray10);
                                break;
                        }
                        record = sr.ReadLine();
                    }
                }
                catch (IOException e)
                {
                    new SpeechSynthesizer().Speak("对不起，你的程序出现了异常，原因是" + e.ToString());
                }
                finally
                {
                    if (sw != null)
                    {
                        sw.Close();
                    }
                    if (sr != null)
                    {
                        sr.Close();
                    }
                    if (fs != null)
                    {
                        fs.Close();
                    }
                }
            }
            if (songExist == true)
            {
                new SpeechSynthesizer().Speak("操作已成功，歌曲" + song + "已经从所有列表中删除");
            }
            else
            {
                new SpeechSynthesizer().Speak("不好意思，歌曲" + song + "不存在播放列表中");
            }
            this.axWindowsMediaPlayer1.Ctlcontrols.play();
        }        #region 删除歌曲的程序调用函数 deleteSong(String[] s, Char[] spliter, String record, String fileURL, String song, bool songExist)
        private void deleteSong(FileStream fs, StreamWriter sw, StreamReader sr, String[] s, Char[] spliter, String record, String fileURL, String song, ArrayList recordArray)
        {
            if (song == s[0])
            {
                /*
                songExist = true;
                String fileContent = sr.ReadToEnd();
                char[] split = new Char[] {'\n'};
                String[] records = fileContent.Split(split);
                fs.SetLength(0);
                sw.Write(fileContent);
                recordArray.Remove(record);
                MessageBox.Show(fileContent);
                 */
                List<String> lst = new List<string>(File.ReadAllLines(fileURL));
                foreach (String deleteRecord in lst)
                {
                    if (deleteRecord == record)
                        lst.Remove(deleteRecord);
                }
                File.WriteAllText(fileURL, lst.ToString());
                    for (int i = 0; i < this.axWindowsMediaPlayer1.currentPlaylist.count; i++)
                    {
                        if (this.axWindowsMediaPlayer1.currentPlaylist.Item[i].ToString() == s[0])
                        {
                            this.axWindowsMediaPlayer1.currentPlaylist.removeItem(this.axWindowsMediaPlayer1.currentPlaylist.get_Item(i));
                        }
                    }
                    //s = record.Split(spliter);
                    new SpeechSynthesizer().Speak("操作已成功，歌曲" + song + "已被删除");
            }
            else
            {
                new SpeechSynthesizer().Speak("不好意思，您要删除的歌曲不存在播放列表中！");
            }
        }