InstallAware

I want to calculate the free disk space dependig on a directory selected in a destination dialog. Therefore I set a variable to 8.589.934.592 Bytes which is exactly 8 GigaByte, means my installation requires fixed 8 GB.

In an example case the Windows Explorer shows up 3.758.305.280 Bytes of free space, so the free disk space for this scenario should be 3.758.305.280 Bytes minus 8.589.934.592 Bytes = -4.831.629.312 Bytes. But, the destination dialog shows up -4.831.137.792, a mathematics control shows up -4.831.170.560.

Question: What is wrong here?

One thing I'm noticing is that the disk space may change as the IA setup runs.

I noticed that the disk space was changing as I ran the installer. I imagine that the OS is caching data to the hard drive (I've got quite a few apps open, so memory is probably hard to come by). When I got to the messagebox displaying the math/data, it seemed "wrong", but when I clicked on the display for the properties of C: drive, the values updated to match the messagebox I had displaying the size...

So, try to view the disk space in the properties for the drive after you reach the point where you're getting your result to verify if this is the case or not.