filepath := PathJoin(['C:', 'path1', 'path2\', 'a.doc']);

// filepath = 'C:\path1\path2\a.doc'

代码：

function PathJoin(const Args: array of string): string;

var

  len: Integer;

  i: Integer;

  s: string;

begin

  s := '';

  len := length(Args);

  for i :=  to len- do

  begin

    if s = '' then

    begin

      s := s + Args[i]

    end

    else

    begin

      if Args[i] <> '' then

        s := IncludeTrailingPathDelimiter(s) + Args[i];

    end;

  end;

  Result := s;

end;