[ILUG] how to clear space at end of line?

[RenWei]

hi ,
  i have some c file in dos format ,  when i try to compile it in linux  ,
it always reports there's some whitespace after "\", like this:

#define pss(x)         \
  if(1)  {      \
  grab_stmof(x)   \
......                    \

 }

it's bothering , so i use
 cat file |col -b > file.new
to clear them , but the whitespaces in file are replace by tab, i don't want
this.

how to clear these whitespace at tail, without  change the normal
whitespace?
is  sed usable, or tr? any one can tell me how to do?