写入TXT文件与StreamWriter的和的FileStream [英] Writing to txt file with StreamWriter and FileStream

问题描述

我使用的时候遇到了一些有趣的一个的StreamWriter 与的FileStream 将文本追加到现有文件。 NET 4.5（有没有试过任何旧框架）。我尝试了两种方式，一种努力，一个没有。我想知道这两者之间的区别是什么。

这两种方法都包含在下面的代码在顶部

 如果$ b $使用b（File.Create（文件路径））（File.Exists（文件路径）！）; 
  

我有一个使用语句创建。因为我通过亲身体验，这是确保应用程序完全关闭该文件的最佳途径找到

非工作方法：

 使用（的FileStream F =新的FileStream（文件路径，FileMode.Append，FileAccess.Write））
（新的StreamWriter（F））。的WriteLine（ somestring）; 
  

通过这种方法没有最终被附加到文件。

工作方式：

 使用（的FileStream F =新的FileStream（文件路径，FileMode.Append，FileAccess.Write ））使用
（StreamWriter的S =新的StreamWriter（F））
 s.WriteLine（somestring）; 
  

我已经做了一些谷歌搜索，不知道相当该怎么寻找，却没有发现任何信息。那么，为什么是匿名的StreamWriter 失败，其中（非匿名？命名？）的StreamWriter 和<？ / p>

解决方案

这听起来像你没有刷新流。

< A HREF =http://msdn.microsoft.com/en-us/library/system.io.stream.flush.aspx> http://msdn.microsoft.com/en-us/library/system.io .stream.flush.aspx

它看起来像的StreamWriter写入到最终目的地，在这种情况下，该文件之前写入的缓冲器。您还可以设置自动刷新属性，而不必明确刷新它。

的 http://msdn.microsoft.com/en-us/library/system.io.streamwriter.autoflush.aspx

要回答你的问题，当你使用使用块，它调用Dispose上的StreamWriter，它必须依次调用刷新。

I ran into something interesting when using a StreamWriter with a FileStream to append text to an existing file in .NET 4.5 (haven't tried any older frameworks). I tried two ways, one worked and one didn't. I'm wondering what the difference between the two is.

Both methods contained the following code at the top

if (!File.Exists(filepath))
    using (File.Create(filepath));

I have the creation in a using statement because I've found through personal experience that it's the best way to ensure that the application fully closes the file.

Non-Working Method:

using (FileStream f = new FileStream(filepath, FileMode.Append,FileAccess.Write))
    (new StreamWriter(f)).WriteLine("somestring");

With this method nothing ends up being appended to the file.

Working Method:

using (FileStream f = new FileStream(filepath, FileMode.Append,FileAccess.Write))
    using (StreamWriter s = new StreamWriter(f))
        s.WriteLine("somestring");

I've done a bit of Googling, without quite knowing what to search for, and haven't found anything informative. So, why is it that the anonymous StreamWriter fails where the (non-anonymous? named?) StreamWriter works?

解决方案

It sounds like you did not flush the stream.

http://msdn.microsoft.com/en-us/library/system.io.stream.flush.aspx

It looks like StreamWriter writes to a buffer before writing to the final destination, in this case, the file. You may also be able to set the AutoFlush property and not have to explicitly flush it.

http://msdn.microsoft.com/en-us/library/system.io.streamwriter.autoflush.aspx

To answer your question, when you use the "using" block, it calls dispose on the StreamWriter, which must in turn call Flush.

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