prolog read from file throws error on special characters

Question

I am working in Prolog, and am trying to read in from a file. The first line is a password. With the password, I want to be able to use special characters.

Here is the read file code:

readfile(Filename):-  
    open(Filename, read, Str),  
    read(Str, Thepassword),  
    read(Str, Thefirewall),  
    close(Str),   
    nb_setval(password, Thepassword),  
    nb_setval(firewall, Thefirewall).  

This works fine until I change the password from brittany to britta!y, then I get ERROR: computer1.txt:1: Syntax error: Operator expected.

Anyone know what I should do?

Answer 1

read/2 reads Prolog terms. What you probably want is to read the whole line regardless it is in Prolog syntax or not.

In SWI Prolog you can use the predicate read_line_to_codes/2 instead. (See the SWI manual entry). You must include the library with use_module(library(readutil)) first.

SICStus has a similar predicate called read_line/1/2.

If you need an atom instead of a list of codes, you can convert it with atom_codes/2.