在内存中操作文本文件的最佳方法：首先读取为byte []？ 读为File.ReadAllText（）然后保存为二进制？

Question

I need to change a file in memory, and currently I read the file to memory into a byte[] using a filestream and a binaryreader.

I was wondering whats the best approach to change that file in memory, convert the byte[] to string, make changes and do an Encoding.GetBytes()? or Read the file first as string using File.ReadAllText() and then Encoding.GetBytes()? or any approach will work without caveats?

Any special approaches? I need to replace specific text inside files with additional chars or replacement strings, several 100,000 of files. Reliability is preferred over efficiency. Files are text like HTML, not binary files.

Answer 1

Read the files using File.ReadAllText() , modify them, then do byte[] byteData = Encoding.UTF8.GetBytes(your_modified_string_from_file) . Use the encoding with which the files were saved. This will give you an array of byte[] . You can convert the byte[] to a stream like this:

MemoryStream stream = new MemoryStream();
stream.Write(byteData, 0, byteData.Length);

Edit: It looks like one of the Add methods in the API can take a byte array, so you don't have to use a stream.

Answer 2

You're definitely making things harder on yourself by reading into bytes first. Just use a StreamReader. You can probably get away with using ReadLine() and processing a line at a time. This can seriously reduce your app's memory usage, especially if you're working with that many files.

using (var reader = File.OpenText(originalFile))
using (var writer = File.CreateText(tempFile))
{
    string line;
    while ((line = reader.ReadLine()) != null) 
    {
        var temp = DoMyStuff(line);
        writer.WriteLine(temp);
    }
}

File.Delete(originalFile);
File.Move(tempFile, originalFile);

Answer 3

Based on the size of the files, I would use File.ReadAllText to read them and File.WriteAllText to wirte them. This frees you up from the responsibility of having to call Close or Dispose on either read or write.

Answer 4

You generally don't want to read a text file on a binary level - just use File.ReadAllText() and supply it with the correct encoding used in the file (there's an overload for that). If the file encoding is UTF8 or UTF32 usually the method can automatically detect and use the correct endcoding. Same applies to writing it back - if it's not UTF8 specify which encoding you want.