更改txt文件并将其保存的快速方法

问题描述

我有txt文件(65mb)，我需要逐行阅读并更改每一行，例如，我有很多行

I have txt file(65mb)i need to read line by line and change each line,For example i have many lines

User=value Password=value  Phone=123456789
User=value Password=value  Phone=123456789
User=value Password=value  Phone=123456789

并且我需要将信用卡/电话的第一个号码更改为*(出于安全原因)，并获取像这样的文本并保存，或者只是更改原始文本文件.

and i need to change first number of credit card/Phone to*(security reason), and get text like this and save it, or just to change origin text file.

User=value Password=value  Phone=*****6789
User=value Password=value  Phone=*****6789
User=value Password=value  Phone=*****6789

我建立了新的字符串，并比保存的逐行添加(更改了)，但这花了我很多时间，这是我的代码

I build new string and add to there line(changed) by line than save, but it take me to many time this is my code

 string NewPath = "";
        string lineOfText;
        string NewTextFile = "";
        using (var filestream = new FileStream(FilePath,
                             FileMode.Open,
                             FileAccess.Read,
                             FileShare.ReadWrite))
        {
            var file = new StreamReader(filestream, Encoding.UTF8, true, 128);

            while ((lineOfText = file.ReadLine()) != null)//here i reading line by line
            {
                NewTextFile += lineOfText.Substring(0, 124) + "************" +
                lineOfText.Substring(136, lineOfText.Length - 136);
                NewTextFile += Environment.NewLine;//here i make new string
            }
        }

        NewPath = FilePatharr[1] + "\\temp.txt";
        System.IO.File.WriteAllText(NewPath, NewTextFile);//here i save him

有谁知道做这件事的更好的方法，我的代码要花很长时间才能保存这个大文件.
更新

Do any one know better way to do this,my code is taking to long to save this big file.
UPDATE

为什么我对这个问题的回答是-2?这个问题怎么了?我在这里只看到关于如何传递敏感数据的错误答案，以及其他不属于该问题的内容.问题是->快速更改txt文件并保存它的方式

Why do i get -2 for this question? Whats wrong with this question? I see here only wrong answers about how to pass sensitive data and more things that not belong to this questions When the question was -->Fast way to change txt file and save it

通过任何方式，我都能找到如何将文件speedUp从100kb \ sec保存到3MB \ sec的速度，这花了我20秒而不是20分钟的时间

Any way i find out how to do this speed of saving file speedUp from 100kb\sec to 3MB\sec now it taking me 20sec and not 20min like before

推荐答案

您的主要问题是要追加到字符串.这很快就变得昂贵.您应该能够在大约五秒钟内处理该65 MB.这就是我要做的:

Your primary problem here is that you're appending to a string. And that gets expensive very quickly. You should be able to process that 65 MB in about five seconds. Here's what I would do:

string outputFileName = "temp.txt";
using (var outputFile = new StreamWriter(outputFileName))
{
    foreach (var line in File.ReadLines(inputFileName))
    {
        var newLine = line.Substring(0, 124) + "************" +
                    line.Substring(136, lineOfText.Length - 136);
        outputFile.WriteLine(newLine);
    }
}

这将比附加字符串快得多.如果您真的想在内存中完成所有操作，请使用StringBuilder.代替

This is going to be a lot faster than appending strings. If you really want to do it all in memory, then use a StringBuilder. Instead of

string NewTextFile = "";

使用

StringBuilder NewTextFile = new StringBuilder();

在编写输出时，将字符串连接替换为:

And when you're composing the output, replace the string concatenation with:

NewTextFile.AppendLine(
    lineOfText.Substring(0, 124) + "************" +
    lineOfText.Substring(136, lineOfText.Length - 136));

最后，将其写入文件:

System.IO.File.WriteAllText(NewPath, NewTextFile.ToString());

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