格式化的文本文件，如何我完成解析它更新文件？ [英] Formatting a text file, how to update the file after I finished parsing it?

问题描述

我将如何打开一个文件，对文件进行一些正则表达式，然后保存文件？

How would I open a file, perform some regex on the file, and then save the file?

我知道我可以打开一个文件，一行读线，但我将如何更新文件的实际内容，然后保存文件？

I know I can open a file, read line by line, but how would I update the actual contents of a file and then save the file?

推荐答案

下面的方法将不管工作反正文件大小，也不会破坏原来的文件，如果完成之前该操作将失败：

The following approach would work regardless of file size, and will also not corrupt the original file in anyway if the operation would fail before it is complete:

string inputFile = Path.Combine(Environment.GetFolderPath(
        Environment.SpecialFolder.MyDocuments), "temp.txt");
string outputFile = Path.Combine(Environment.GetFolderPath(
        Environment.SpecialFolder.MyDocuments), "temp2.txt");
using (StreamReader input = File.OpenText(inputFile))
using (Stream output = File.OpenWrite(outputFile))
using (StreamWriter writer = new StreamWriter(output))
{
    while (!input.EndOfStream)
    {
        // read line
        string line = input.ReadLine();
        // process line in some way

        // write the file to temp file
        writer.WriteLine(line);
    }
}
File.Delete(inputFile); // delete original file
File.Move(outputFile, inputFile); // rename temp file to original file name

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