Re: double_quotes doesnt return codes in SWI-Prolog

On 2005-05-21, blindsearch <dpatte3@xxxxxxxxxxx> wrote:
> I'm using SWI-Prolog 5.4.7, i've read the manual and the default
> behaviour for double_quotes is to return the code i.e "A" -> 65.

Note that it creates a _list_:

"A" --> [65]

> This works if I'm using the Prolog prompt but in my code, it doesnt,
> I've tried setting it set_prolog_flag(double_quotes,codes)
> it doesnt work, I've tried setting it to all the other possible values,
> nothing works.
>
> Here's my code:
>
> read_entrys("@",Stream) :- % after @, read in the type
> !, get0(Stream,C), read_type(C,Stream).
> read_entrys(_C,Stream) :- % ignore anything else
> read_entrys(Stream).
>
> The first clause never unifies.
> I don't want to resort to read_entrys(64,Stream) ...

You want a character:

read_entrys(0'A, Stream) :-
...

The double-quotes flag works just fine:

:- set_prolog_flag(double_quotes, codes).

codes :-
writeln("codes").

:- set_prolog_flag(double_quotes, chars).

chars :-
writeln("chars").

1 ?- codes.
[99, 111, 100, 101, 115]

Yes
2 ?- chars.
[c, h, a, r, s]

Cheers --- Jan
.

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