Normalize file path with WinAPI

Question

Given two file path strings with potentially different casing and slashes ('\' vs '/'), is there a quick way (that does not involve writing my own function) to normalize both paths to the same form, or at least to test them for equivalence?

I'm restricted to WinAPI and standard C++. All files are local.

Answer 1

To write the least amount of code, you could write a binary predicate that compares to chars as equal if they differ only in case or are both one of the slashes. Then use the stl algorithm equal to do the comparison, and pass in the predicate.

Answer 2

There are odd cases. For example, "c:\windows..\data\myfile.txt" is the same as "c:\data.\myfile.txt" and "c:\data\myfile.txt". You can have any number of "\.\" and "\..\" in there. You might look into the Windows API function GetFullPathName. It might do canonicalization for you.

Answer 3

Depending on whether the paths could be relative, or contain "..", or junction points, or UNC paths this may be more difficult than you think. The best way might be to use the GetFileInformationByHandle() function as in this answer.

Edit: I agree with the comment by RBerteig that this may become hard to impossible to do if the paths are not pointing to a local file. Any comment on how to safely handle this case would be greatly appreciated.

Answer 4

May I suggest PathCanonicalize?