高分求！！提取txt中多条记录的每条记录的前8个字符。

Question

你比方说给出txt中3条如下所示的记录：
11111111：tttttttttttttttttttttt:rrrrrrrrrrrrrrrrrrrrrrrr?yyyyyyyyyyyyyyyyyyyyyyyyyy:ttttttttttt:yyyyyyyyyyyyyyyyyyyy:77777777:88888888:::::::::4444444
22222222:ttttttttttttttttttt:444444444444:%ppppppppp:66666666666666666666666666666666666666666666666666666666666
33333333:444444444444444444444444444444444444444444444444444"55555555555555555555555"^hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
怎样提取出信息存在另一个txt中，信息如下：
11111111
22222222
33333333小弟不熟悉c#，麻烦请给出可行的代码，谢谢！！

Answer 1

using(StreamReader sr = new StreamReader("你的原文件.txt"))
{   
using(StreamWriter sw = new StreamWriter("你的新文件"))
while(sr.Peek() > 0)
{
string Data = sr.ReadLine();
sw.WriteLine(Data.Substring(0,8));
        }
}

Answer 2

读取每一行，然后Substring取前8个

Answer 3

C# codeusing(StreamReader sr = new StreamReader("你的原文件.txt"))
{   
    using(StreamWriter sw = new StreamWriter("你的新文件"))
    while(sr.Peek() > 0)
    {
        string Data = sr.ReadLine();
        sw.WriteLine(Data.Substring(0,8));
        }
}
正解

Answer 4

运行显示
sw.WriteLine(Data.Substring(0, 8)); 未处理ArgumentOutOfRangeException    索引和长度必须引用该字符串内的位置。
参数名: length怎么回事儿啊？？、

Answer 5

加个判断啊
if(Data.Length >=8)
  sw.WriteLine(Data.Substring(0,8));
PS:文本最后如果多加了几个换行符就会这样。

Answer 6

 StreamWriter sw = new StreamWriter(Server.MapPath("新文件.txt"));
        StreamReader str = new StreamReader(Server.MapPath("旧文件.txt"));
        while (str.Peek() > 0)
        {
            string ss = str.ReadLine();
            sw.WriteLine(ss.Substring(0,8));
        }
        sw.Close();

Answer 7

text.txt
11111111：tttttttttttttttttttttt:rrrrrrrrrrrrrrrrrrrrrrrr?yyyyyyyyyyyyyyyyyyyyyyyyyy:ttttttttttt:yyyyyyyyyyyyyyyyyyyy:77777777:88888888:::::::::4444444
22222222:ttttttttttttttttttt:444444444444:%ppppppppp:66666666666666666666666666666666666666666666666666666666666
33333333:444444444444444444444444444444444444444444444444444"55555555555555555555555"^hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
44444444:444444444444444444444444444444444444444444444444444"55555555555555555555555"^hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh //行番号
        int iLine = 0;
        try
        {
            string path = @"D:\test.txt";//读取文件txt
            string savepath = @"D:\test1.txt";//存放文件txt
            using (FileStream fs = new FileStream(path, FileMode.Open))
            {
                using (StreamReader sr = new StreamReader(fs))
                {
                    while (!sr.EndOfStream)
                    {
                        iLine++;
                        string sLine = sr.ReadLine();
                        if (sLine.Length < 1)
                        {
                            continue;
                        }
                        if (iLine % 2 == 0)//隔行读取
                        {
                            string sRecordKbn = sLine.Substring(0, 8);//截取的数据
                            //另存到其他txt文件中
                            if (File.Exists(savepath))
                            {
                                File.AppendAllText(savepath, sRecordKbn + "\r\n");
                            }
                        }
                    }
                }
            }          
        }
        catch (Exception ex)
        {            Response.Write(ex.Message);
        }
test1.txt
22222222
44444444

Answer 8

http://msdn.microsoft.com/zh-cn/library/6aetdk20.aspx
http://msdn.microsoft.com/zh-cn/library/system.io.file.appendtext(v=VS.80).aspx
详情参考以上网址。
File.AppendAllText(savepath, sRecordKbn + "\r\n");可以改成
using (StreamWriter sw = File.AppendText(savepath))
{
   sw.WriteLine(sRecordKbn + "\r\n");
}

Answer 9

提示错误 1 当前上下文中不存在名称“Response”

Answer 10

提示错误 1 当前上下文中不存在名称“Response” 啊。怎么解决。我不熟悉c#

Answer 11

 Response.Write(ex.Message);
注释掉

Answer 12

 //行番号
            int iLine = 0;
            #region/////////////////////////第一种
            string path = @"D:\test.txt";//读取文件txt
            string savepath = @"D:\test1.txt";//存放文件txt
            using (FileStream fs = new FileStream(path, FileMode.Open))
            {
                using (StreamReader sr = new StreamReader(fs))
                {
                    while (!sr.EndOfStream)
                    {
                        iLine++;
                        string sLine = sr.ReadLine();
                        if (sLine.Length < 1)
                        {
                            continue;
                        }
                        if (iLine % 2 == 0)
                        {
                            string sRecordKbn = sLine.Substring(0, 8);//截取的数据
                            //另存到其他txt文件中
                            if (File.Exists(savepath))
                            {
                                using (StreamWriter sw = File.AppendText(savepath))
                                {
                                    sw.WriteLine(sRecordKbn);
                                }
                            }                        }
                    }
                }
            }
            #endregion
            #region /////////////////////////第二种改正
            using (StreamReader sr = new StreamReader(@"D:\test.txt"))//读取文件txt
                {
                    while (!sr.EndOfStream)
                    {
                        iLine++;
                        string sLine = sr.ReadLine();
                        if (sLine.Length < 1)
                        {
                            continue;
                        }
                        if (iLine % 2 == 0)
                        {
                            string sRecordKbn = sLine.Substring(0, 8);//截取的数据
                            if (File.Exists(@"D:\test1.txt"))//提出数据存放文件txt
                            {
                                using (StreamWriter sw = File.AppendText(@"D:\test1.txt"))
                                {
                                    sw.WriteLine(sRecordKbn);
                                }
                            }
                            else//文件不存在创建文件
                            {
                                FileStream fs;
                                fs = File.Create(@"D:\test1.txt");//创建不要用file创建
                                //使用File.Create创建再复制/移动/删除时会提示：文件正由另一进程使用,因此该进程无法访问该文件
                                //改用 FileStream 获取 File.Create 返回的 System.IO.FileStream 再进行关闭就无此问题
                                fs.Close();
                                using (StreamWriter sw = File.AppendText(@"D:\test1.txt"))
                                {
                                    sw.WriteLine(sRecordKbn);
                                }
                            }
                        }
                    }
                }
            #endregion
看看那个适合你。用哪个吧

Answer 13

if(Data.Length >=8)
  sw.WriteLine(Data.Substring(0,8));