read next line if first charcter is semicolon

What does the file look like? You might be able to use lineread() which uses the SKILL parser to read the file - and if it contains blank lines or SKILL-like comments, it will return t rather than the contents of the line...

Andrew.

I've no idea what ".sexp" file is, but if you had a file that looked like this (say):

; some comments
a b c
; some more comments
; and some more
/* and even
some
C-like comments */
1 2 3 ; ignore this bit at the end of the line

you could do:

port=infile("myfile")
when(port
  while(data=lineread(port)
    unless(data==t
      printf("elements on the line were: %L\n" data)
    )
  )
)
close(port)

It will then output:

elements on the line were: (a b c)
elements on the line were: (1 2 3)

You should read the documentatin on lineread. This won't work if it's not in SKILL-like syntax. If you want to general line-by-line reading and returning a string, you could do:

port=infile("myfile")
when(port
  while(gets(line port)
    unless(substring(line 1 1)==";"
       printf("The line that was read was: %s" line)
    )
  )
  close(port)
)

Then this outputs:

The line that was read was: a b c
The line that was read was: /* and even
The line that was read was: some
The line that was read was: C-like comments */
The line that was read was: 1 2 3 ; ignore this bit at the end of the line

Note that gets() will include the carriage return in the string that was read.

So your mileage may vary - you can do whatever you want, but you'll just need to code it appropriately. You could also use the rex.* functions or pcre.* functions (in IC61X for pcre) to use pattern matching if that's easier.

Regards,

Andrew.