How to Find and Close an open Office document via Office Automation

I have a program that will take the files in a directory and upload them to a server. If the file is a Word File, I would then like to detect if the file is open in word / excel etc. If it is 开发者_JAVA百科open, I would like to be able to then close it, in order to delete the local copy of the file.

Any ideas how to do this? The program responsible for the detection and closing of the documents is a win forms app.

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Perhaps How to use Visual C# to automate a running instance of an Office program