Why does StreamWriter overwrite my file?
c#, filestream, streamwriter
Solution
If you use `FileMode.Create`, according to MSDN:
Specifies that the operating system should create a new file. If the file already exists, it will be overwritten. This requires FileIOPermissionAccess.Write permission. FileMode.Create is equivalent to requesting that if the file does not exist, use CreateNew; otherwise, use Truncate. If the file already exists but is a hidden file, an UnauthorizedAccessException exception is thrown.
So you need to use `FileMode.Append` instead, if you want to add content to the end of the file:
Opens the file if it exists and seeks to the end of the file, or creates a new file. This requires FileIOPermissionAccess.Append permission. FileMode.Append can be used only in conjunction with FileAccess.Write. Trying to seek to a position before the end of the file throws an IOException exception, and any attempt to read fails and throws a NotSupportedException exception.
FileStream fs = new FileStream(filename, FileMode.Append, FileAccess.Write);
Problem
I'm using `SteamWriter` to write something to a text file, however its overwriting the old data with the new data. How can I make sure it will just add the new data instead of overwriting the old data? my code: ``` class Program { const string filename = @"C:\log.txt"; static void Main() { FileStream fs; fs = new FileStream(filename, FileMode.Create, FileAccess.Write); StreamWriter writer = new StreamWriter(fs); writer.WriteLine("test"); writer.Close(); fs.Close(); } } ```