清除文件的内容

You can use the File.WriteAllText method.

System.IO.File.WriteAllText(@"Path/foo.bar",string.Empty);

Try using something like

File.Create

Creates or overwrites a file in the specified path.

The simplest way to do this is perhaps deleting the file via your application and creating a new one with the same name... in even simpler way just make your application overwrite it with a new file.

Use FileMode.Truncate everytime you create the file. Also place the File.Create inside a try catch.

This is what I did to clear the contents of the file without creating a new file as I didn't want the file to display new time of creation even when the application just updated its contents.

FileStream fileStream = File.Open(<path>, FileMode.Open);


/*
* Set the length of filestream to 0 and flush it to the physical file.
*
* Flushing the stream is important because this ensures that
* the changes to the stream trickle down to the physical file.
*
*/
fileStream.SetLength(0);
fileStream.Close(); // This flushes the content, too.

The easiest way is:

File.WriteAllText(path, string.Empty)

However, I recommend you use FileStream because the first solution can throw UnauthorizedAccessException

using(FileStream fs = File.Open(path,FileMode.OpenOrCreate, FileAccess.ReadWrite))
{
lock(fs)
{
fs.SetLength(0);
}
}