问题
I have the below program that will move files from one directory to other. In sysnchronous way, it works fine.But I want to do it in the asynchronous way.
Thanks
回答1:
The error says it all: you can't await something that is void. You can only await Tasks and things that look similar to Tasks (e.g. YieldAwaitable, that's returned by Task.Yield()). But you most certainly can't await void.
There doesn't seem to be a way to asynchronously move a file in .Net 4.5.
The best you can do is to either use something like await Task.Run(() => fileinfo.MoveTo(target)), which will still block a thread, but not the current one (may be useful if you're on the UI thread).
Or, alternatively, you could copy the file yourself using Streams (which can be asynchronous) and then delete the original.
回答2:
You can only use await when the method you are calling supports it.
To support await the method needs to return a Task<T>
In this case the fileInfo.MoveTo does not return a Task
来源：https://stackoverflow.com/questions/11167783/cannot-apply-await-and-async-properly-in-c5-0