Overview

I/O methods throw these exceptions:

• IOException — the base class of all System.IO exceptions
• FileNotFoundException
• DirectoryNotFoundException
• DriveNotFoundException
• PathTooLongException
• OperationCanceledException
• UnauthorizedAccessException

I/O methods wrap calls to the underlying operating system. If an I/O error occurs in code executed by the OS, the OS returns error information to the .NET I/O method. This error maps to a .NET exception type. For example, on Windows, ERROR_FILE_NOT_FOUND (0x02) maps to FileNotFoundException. However, the precise conditions under which this mapping succeeds varies. Always catch IOException last in your catch blocks.

IOException

IOException contains additional error information in its HResult property:

The HResult value can be converted to a Win32 error code by stripping out the upper 16 bits of the 32-bit value:

// ...
catch (IOException e) when ((e.HResult & 0x0000FFFF) == 32)
{
    Console.WriteLine("There is a sharing violation.");
}
// ...