How to expand a path with \..\ in it

Question

I have this path :

c:\dev\myapp\dirA\..\dirB\myfile.txt

how to expand it to :

c:\dev\myapp\dirB\myfile.txt

Is their any Delphi functions to do this or any winapi function ?

`RtlDosPathNameToNtPathName_U_WithStatus` normalize path (but convert it to nt form) here question - for what you need this and how want use — RbMm, Oct 20 '22 at 22:26
@RbMm i need it because i want to calculate the relative path from c:\dev\myapp\dirA\..\dirB\myfile.txt to c:\dev\myapp\dirB\ that will be simply myfile.txt — zeus, Oct 20 '22 at 22:29
use `RtlDosPathNameToNtPathName_U_WithStatus` for normalize path. remove \..\ \.\ convert / to \ etc — RbMm, Oct 20 '22 at 22:44
`PathCchCanonicalize`, or open the file then use `GetFinalPathNameByHandle`. — Jonathan Potter, Oct 20 '22 at 23:05
@AndreasRejbrand - yes, undocumented. buf this not mean "volatile" — RbMm, Oct 20 '22 at 23:20
@AndreasRejbrand It's not just undocumented, it's also not part of the Win32 API. — IInspectable, Oct 21 '22 at 06:15

score 10 · Accepted Answer · edited Oct 21 '22 at 01:37

10

ExpandFileName('c:\dev\myapp\dirA\..\dirB\myfile.txt');

Result:

c:\dev\myapp\dirB\myfile.txt

edited Oct 21 '22 at 01:37

Remy Lebeau

answered Oct 21 '22 at 00:07

Ivan Yuzafatau

1

On Windows, `ExpandFileName()` simply calls the Win32 [`GetFullPathName()`](https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-getfullpathnamew) function to handle all of the normalizing. On other platforms, `ExpandFileName()` actually parses the string and does all the normalizing manually. – Remy Lebeau Oct 21 '22 at 01:41
1

[FPCs `ExpandFileName()`](https://www.freepascal.org/docs-html/rtl/sysutils/expandfilename.html) also parses manually, even resolving `...` and `~`. WinAPI wise see [How do you remove directory qualifiers to simplify pathname using the Win32 API?](https://stackoverflow.com/q/6599458/4299358), including comments. – AmigoJack Oct 21 '22 at 06:36

1 Answers1