Get free disk space

Hello, i am looking for a function to get free disk space on a selected volume, but i can’t find none native. So i found this: http://stackoverflow.com/questions/1732717/how-to-determine-how-much-free-space-on-a-drive-in-qt (ticked answer). I like the solution, because the application will run on windows. But what headers do i have to add? What lines in the .pro ? Thank you! This is the API http://msdn.microsoft.com/en-us/library/windows/desktop/aa364935(v=vs.85).aspx