Conversion between absolute and relative paths in Delphi

Question

Are there standard functions to perform absolute <--> relative path conversion in Delphi?

For example:

• \'Base\' path is \'C:\\Projects\\Projec

Answer 1

For what it's worth, my codebase uses SysUtils.ExtractRelativePath in one direction and the following home-grown wrapper coming back:

function ExpandFileNameRelBaseDir(const FileName, BaseDir: string): string;
var
  Buffer: array [0..MAX_PATH-1] of Char;
begin
  if PathIsRelative(PChar(FileName)) then begin
    Result := IncludeTrailingBackslash(BaseDir)+FileName;
  end else begin
    Result := FileName;
  end;
  if PathCanonicalize(@Buffer[0], PChar(Result)) then begin
    Result := Buffer;
  end;
end;

You'll need to use the ShLwApi unit for PathIsRelative and PathCanonicalize.

The call to PathIsRelative means that the routine is robust to absolute paths being specified.

So, SysUtils.ExtractRelativePath can be your AbsToRel only the parameters are reversed. And my ExpandFileNameRelBaseDir will serve as your RelToAbs.