WinAPI: How to Get the Amount of Space Available on a Disk Volume (GetDiskFreeSpaceEx)

The following method shows how to get the amount of space available on a disk volume. We use a method imported from kernel32: GetDiskFreeSpaceEx:

[DllImport("kernel32.dll", CharSet=CharSet.Auto, SetLastError=true)]
internal static extern bool GetDiskFreeSpaceEx(string drive, 
    out long freeBytesForUser, 
    out long totalBytes, 
    out long freeBytes);

If it returns false - there was an exception calling the method. freeBytesForUser is what we are looking for. Starting from .NET 2.0 there is a managed class called System.IO.DriveInfo with property AvailableFreeSpace which uses the same method from kernel32.

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