need tips and examples for reading a text file

getchar returns a character not a string so do
getchar(s 1) == '\(

also since a paren is special in Skill it needs to be escaped by a backslash, to match a 'd' all you would need is a 'd

Some other options:
1) use substring instead of getchar.
substring(s 1 1) == "("
2) convert the getchar result to a string
get_string(getchar(s 1)) == "("

Thanks! Another - even more general - question.
I've got a major brain freeze going here.

I'm using a while to read a text file (the variants.lst file). In this example I look at the first character of each line and  see if it is an open paren.

     xx = infile("variants.lst")
     count = 0
     while(xx
         gets(s xx)
         lineno = count++
         if(substring(s 1 1)=="("
            then
            printf("Line #%d starts with a \"(\"\n" lineno)
            else
            printf("Line #%d doesn't start with a \"(\"\n" lineno)
         ); end if
     ); end while

Problem is that after the last line of the infile is read I get:
E- *Error* substring:
argument #1 should be either a string or a symbol (type template = "Sx") - nil

The last gets statement has returned a string that is nil.

If I put in an if loop  if(s != nil  after the gets statement the while loop goes forever. How do I evaluate the result of the gets statement before trying to use it?

See if this works:
if( xx = infile("variants.lst") ; make sure we can open the file
then
count = 0
while( gets(s xx)
lineno = count++
if(substring(s 1 1)=="("
then
printf("Line #%d starts with a \"(\"\n" lineno)
else
printf("Line #%d doesn't start with a \"(\"\n" lineno)
); end if
); end while
close(xx); close out the input port
); end if