how do i make my program startup before logging in?

I need to create a program that runs before a user logged in. I want to create that p开发者_如何学编程rogram in C#. Can someone give me a hint where and how to start.

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You have to write a Windows Service. Choose Project type Visual C#->Windows->Windows Service and have a look at MSDN what you have to implement

Introduction to Windows Service Applications

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You would need to use a windows service. Once you understand the concept it's easy. Basically it's an application that runs in the background (no UI) and is started from Windows.