In Prolog, there is no way to:

Prompt the user to type a string (including spaces) on screen and get it
after the user press Return (not require ".").

Am I right?

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Before you buy.

I hope not :-)  read/1 reads Prolog-terms.  To read anything else you need
to use one of the character-reading predicates.  These are:

        get0            Good old Prolog
        get_code        ISO Prolog: read character code
        get_char        ISO Prolog: read one-character atom.

For the good old Prolog (runs on most systems, but nowadays I would use
the ISO versions):

read_line(Line) :-
        read_line(user_input, Line).

read_line(S, Line) :-
        get0(S, C0),
        read_line(C0, S, LineChars),
        name(Line, LineChars).          % or atom_codes or just leave it a string

read_line(10, _, []) :- !.              % \n
read_line(13, _, []) :- !.              % \r
read_line(C0, S, [C0|T]) :-
        get0(S, C1),
        read_line(C1, S, T).

        Regards --- Jan

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jan Wielemaker                Author of SWI-Prolog and the XPCE GUI library
SWI, University of Amsterdam  http://www.swi.psy.uva.nl/projects/SWI-Prolog/

no you're wrong. Check your manual for get/1 in order to read character
by character.

--
Gertjan van Noord Alfa-informatica, RUG,  Postbus 716, 9700 AS Groningen
vannoord at let dot rug dot nl            http://www.let.rug.nl/~vannoord/

I hope not too :-)

I have just tried your code (thanks to you), when I typed a+b, I got
'a+b'....How to make sure I get the same as the input? I need a+b
instead of 'a+b' :-(

Cheers.

Sent via Deja.com http://www.deja.com/
Before you buy.

What did you want? Reading terms or reading text. read/1 is for terms,
the read_line/[1,2] I gave you is for text. If you insist reading a
Prolog term that is newline delimited instead of '. ', you can convert
the read text into a term. This is not standard Prolog. SWI-Prolog
defines atom_to_term/3. Some others (sicstus, quintus) have
with_input_from_chars/2, etc. Check your manual.

        Regards --- Jan

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jan Wielemaker                Author of SWI-Prolog and the XPCE GUI library
SWI, University of Amsterdam  http://www.swi.psy.uva.nl/projects/SWI-Prolog/

Thank you so much.

I didn't know how to explain :-( Now I think what I need is to read a
term delimited with newline. I am going to compile my program into an
exe file for the users who don't know Prolog at all.
Does SWI have something like read_term(Term, delimition=10)?

Cheers.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~
http://www.swi.psy.uva.nl/projects/SWI-Prolog/

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Before you buy.

Try this!!

readString(Cad) :-  readStr(List),
   string_to_list(Cad,List).

readStr(String) :-  get0(Char),
   (Char=10 ->
    String=[]
   ;
    readStr(List),
    String=[Char|List]
   ).

Pablo.