列表中的偶数和奇数元素以及计数元素直到列表中的特定索引，但显示错误
我正在制作一个 prolog 程序来计算列表中的偶数和奇数元素，并将元素计数到列表中的特定索引（用户给定）。但它显示错误。我是序言中的新人。这是我的代码：
is_even(N) :- Y is N mod 2, Y=0.
split(Index,List,Left,Right) :-
length(Left,Index), % Actually CREATES a list of fresh variables if "Left" is unbound
append(Left,Right,List). % Demand that Left + Right = List.
create(L1):-read(Elem),create(Elem,L1).
create(-1,[]):-!. create(Elem,[Elem|T]):-read(Nextel),create(Nextel,T).
setval(Y8,0).
setval(Y9,0).
incr():-
Y8 is Y8 + 1.
incb():-
Y9 is Y9 + 1.
count(R):-
( is_even(R) -> incr();incb()).
dosomething([]).
dosomething([R|T]) :- count(R), dosomething(T).
go:- write('Creating a list'),nl, write('Enter -1 to stop'),nl, create(L), nl, write('Enter index'),read(ID), split(ID,L,X1,X2), dosomething(X1), write(Y8), write(Y9).
它给了我以下错误：
ERROR: Arguments are not sufficiently instantiated
ERROR: In:
ERROR: [14] _19326 is _19332+1
ERROR: [11] dosomething([1,2]) at c:/users/v/documents/prolog/bw.pl:24
ERROR: [10] go at c:/users/v/documents/prolog/bw.pl:26
ERROR: [9] toplevel_call(user:user:go) at c:/program files/swipl/boot/toplevel.pl:1117
ERROR:
ERROR: Note: some frames are missing due to last-call optimization.
ERROR: Re-run your program in debug mode (:- debug.) to get more detail.
I am making a prolog program to count even and odd elements from list and count elements up to a specific index(user given) in the list. But it shows Errors. I am new in prolog. Here is my code:
is_even(N) :- Y is N mod 2, Y=0.
split(Index,List,Left,Right) :-
length(Left,Index), % Actually CREATES a list of fresh variables if "Left" is unbound
append(Left,Right,List). % Demand that Left + Right = List.
create(L1):-read(Elem),create(Elem,L1).
create(-1,[]):-!. create(Elem,[Elem|T]):-read(Nextel),create(Nextel,T).
setval(Y8,0).
setval(Y9,0).
incr():-
Y8 is Y8 + 1.
incb():-
Y9 is Y9 + 1.
count(R):-
( is_even(R) -> incr();incb()).
dosomething([]).
dosomething([R|T]) :- count(R), dosomething(T).
go:- write('Creating a list'),nl, write('Enter -1 to stop'),nl, create(L), nl, write('Enter index'),read(ID), split(ID,L,X1,X2), dosomething(X1), write(Y8), write(Y9).
It gives me the following error:
ERROR: Arguments are not sufficiently instantiated
ERROR: In:
ERROR: [14] _19326 is _19332+1
ERROR: [11] dosomething([1,2]) at c:/users/v/documents/prolog/bw.pl:24
ERROR: [10] go at c:/users/v/documents/prolog/bw.pl:26
ERROR: [9] toplevel_call(user:user:go) at c:/program files/swipl/boot/toplevel.pl:1117
ERROR:
ERROR: Note: some frames are missing due to last-call optimization.
ERROR: Re-run your program in debug mode (:- debug.) to get more detail.
如果你对这篇内容有疑问，欢迎到本站社区发帖提问 参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。
绑定邮箱获取回复消息
由于您还没有绑定你的真实邮箱，如果其他用户或者作者回复了您的评论，将不能在第一时间通知您！
发布评论
评论（1）
您的代码存在几个问题，也许您应该重新考虑一种更简单的方法。
首先，适用于任何编程语言的软件工程原则指出，您应该尽可能避免全局变量。因此，您应该使用 - 例如 -
Yn is Y + 1，而不是incr():- Y8 is Y8 + 1.。另请注意，由于在 Prolog 中变量分配一次，
Y8 is Y8 + 1将永远为真，然后谓词 incr/0 将总是失败。另一个小问题：
incr():-...是一个 SWI-Prolog 语法扩展，引入它是为了支持 OOP 的受限形式，您应该使用普通的 Prolog 语法incr :- ...。无论如何，尝试使用单个“循环”（即递归谓词）来解决您的作业，您可以在其中传递要检查的元素的索引，并返回说明您要求检查的属性的计数器。如果我正确理解了这个问题，您还应该检查元素是否实际上是整数，对它们进行计数，并仅对它们应用奇数/偶数检查。在下面的代码片段中，我使用传统参数排序，将输入放在输出之前。您应该在 count/6 第一个子句的适当位置放置一个剪切，并且 - 当然 - 提供适当的谓词 update_counters/7。
There are several problems with your code, maybe you should rethink it a simpler way.
First, a SW engineering principle valid in any programming language, states that you should avoid global variables, as far as possible. So, instead of
incr():- Y8 is Y8 + 1., you should use - for example -Yn is Y + 1.Note also that since in Prolog variables are assign once,
Y8 is Y8 + 1will never be true, and then the predicate incr/0 will always fail.Another - minor - problem:
incr():-...is a SWI-Prolog syntactic extension, introduced to support a restricted form of OOP, you should use instead the plain Prolog syntaxincr :- ....Anyway, try to solve your assignment with a single 'loop', that is, a recursive predicate, where you pass down the index of the element to check, and get back the counters accounting for the properties you're asked to check. If I understand the question correctly, you should also check that elements are actually integers, count them, and apply the odd/even check only on them. In the following snippet, I use the conventional arguments ordering, placing the input before the output. You should place a cut in the appropriate place in the first clause of count/6, and - of course - provide an appropriate predicate update_counters/7.