CODEWITHSUNDEEP
fileprolog
Byron Picado
Byron Picado

Reputation: 11

Swi Prolog script not execute correctly

I want to read a file and then write another according to the results of the first, but once I read the first file, the program terminates immediately. I have searched for the cause of why it happens, but I have not found anything. I would like to know if someone can help me.

This is the code: 

main :-
   current_prolog_flag(argv, Argv),
   [H|_T] = Argv,
   readPlainText(H),
   getList(L), 
   open('result.txt',write,X),
   write(X, L), nl(X),
   close(X),
   halt.
main :-
   halt(1).

And the script stops after execute this piece of code:

readPlainText(X) :-
   open(X, read, Stream),
   readWords(Stream),
   close(Stream).

I am executing from console: 

swipl -s leer.pl --quiet menciones.txt

EDIT: I think the problem is for at_end_of_stream

readWords(InStream) :-
   \+ at_end_of_stream(InStream),
   readWord(InStream, W),
   write(W), nl,
   addWordToDatabase(W),
   readWords(InStream).

Upvotes: 1

Views: 116

Answers (1)

CapelliC
CapelliC

Reputation: 60004

You're missing the recursion termination. Try

readWords(InStream) :-
  (   \+ at_end_of_stream(InStream)
  ->  readWord(InStream, W),
      write(W), nl,
      addWordToDatabase(W),
      readWords(InStream)
  ;   true
  ).

Or you can keep unchanged your readWords/1, and add - after it - the handler for EOF:

readWords(_InStream).

Then you could test for errors possibily occurring in readWords/1 goals (for instance, in addWordToDatabase/1), that currently would stay hidden.

Upvotes: 1

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