How to check whether the path selected is a drive name

[C++ Programming]

How can I know whether the path selected is a drive name of any other folder . I have a xml whether user can edit it and enter a path. User can enter any path in it like C:\, C:\\\\, or C:\test\abc or anything. I am getting a problem with path comparision I have to treat C:\\\ as C:\ only, Any api to check whether selected path is a drive name. So that I can consider C:\\\ as C:\

Thanks..