var
  fullFileName : string;

begin
  // Set up a full file name with drive and path
  fullFileName := 'C:\Program Files\Borland\Delphi7\Projects\Unit1.dcu';

  // Show the component parts of this full name
  ShowMessage('Drive = '+ExtractFileDrive (fullFileName));
  ShowMessage('Dir   = '+ExtractFileDir   (fullFileName));
  ShowMessage('Path  = '+ExtractFilePath  (fullFileName));
  ShowMessage('Name  = '+ExtractFileName  (fullFileName));
  ShowMessage('Ext   = '+ExtractFileExt   (fullFileName));
end;

Drive = C:
Dir   = C:\Program Files\Borland\Delphi7\Projects
Path  = C:\Program Files\Borland\Delphi7\Projects\
Name  = Unit1.dcu
Ext   = .dcu

var
  oldName, newName : string;

begin
  // Try to rename the current Unit1.dcu to Uni1.old
  oldName := 'Unit1.dcu';
  newName := ChangeFileExt(oldName, '.new');

  // Show the old and new values
  ShowMessage('Old name = '+oldName);
  ShowMessage('New name = '+newName);
end;

Old name = Unit1.dcu
New name = Unit1.new

var
  selectedFile   : string;
  drive          : char;
  path, fileName : string;

begin
  // Ask the user to select a file
  if PromptForFileName(selectedFile)
  then
  begin
    // Display this full file/path value
    ShowMessage('Selected file = '+selectedFile);

    // Split this full file/path value into its constituent parts
    ProcessPath(selectedFile, drive, path, fileName);
    ShowMessage('drive = '+drive);
    ShowMessage('path = '+path);
    ShowMessage('fileName = '+fileName);
  end;
end;

 { The user selects C:\Files\data.txt and hits OK }
   
   Selected file = C:\Files\data.txt
   drive = C
   path = \Files
   filename = data.txt