AutoHotKey: Method of finding file upwards, recursively, using loop

Question

I am working through the AHK docs but am having a hard time finding a fairly simple way to find the path to a target file in a parent directory, given a starting directory.

For example:

Starting in C:\a\b\c\d\e\f\g\

I want to find the path of root.txt where:

C:\a\b\c\root.txt

I want to return C:\a\b\c\

[by the way I do not know where root.txt lives]

Answer 1

I would make a loop and add "..\" to the current directory path each time.
It works in autohotkey, i always use it.

For example, I have my scripts in one directory, and images in another on the same level.
So my images paths are always:

%A_ScriptDir%\..\images\

Answer 2

http://www.autohotkey.com/docs/commands/SplitPath.htm

Your entire path would be the input variable. and your desired path would be given to you as OutDir