function TrimSlashes(s: string; all: Boolean = False): string;
begin
  while (s <> '') and CharInSet(s[1], ['/', '\']) do
    Delete(s, 1, 1);
  if all then
    while (s <> '') and CharInSet(s[length(s)], ['/', '\']) do
      Delete(s, length(s), 1)
  else
    while (s <> '') and (s[length(s)] = '\') do
      Delete(s, length(s), 1);
  Result := s;
end;

如：c:\123\  结果 c:\123
如：http://www.baidu.com/  结果 http://www.baidu.com