How do I access variables in if statements?

Question

Following on from Put variable to line above current line VIm

I added some logic to only run if the begin and end tags in the list are present, snippet

....
let findStart='<'.taglist[s1].'>'
let findEnd='<'.'\/'.ns.taglist[s1].'>'

let fs=0
let fe=0


while something
  let fs=search(expand(findStart))
  let fe=search(expand(findEnd))
  if ( &fs>0 && &fe>0 )
      call search(findStart,'b')
      "paste the beginning fold
      :-1put =foldbegin
      .....
      :let fs=0
      :let fe=0
  endif 
let something=something +1
endwhile

In modeline this :let fs=0|:call search('<')|echo fs returns the position of the search. In Vimscript the only way I can use the variable in an if statement is if ( &fs>0 ... ).

I can't find anything to explain why the statements work differently so I can make sense of it. Any suggestions of where to look for answers?

Also :let fs=0 within the if doesn't reset the variable. Why?

UPDATE: It's something to do with using 2 letter variables but I don't know what the issue is despite googling it.

Answer 1

It would help, if you could include the error message in your question.

When using '&variables' you are effectively accessing option values. See the help at :h expr-option.

So in your if statement you should not use if &fs if you want to check a variable and not the option value 'fsync', but using &fe will cause an error, because there exists no option with that (short-)name.