序言将数字转换为罗马数字 [英] prolog convert numbers into roman numerals

问题描述

我有这段代码可以将整数转换为罗马数字 我需要添加一个将整数与罗马数字输入进行比较的函数，并显示它是否为try或false，例如: 罗马(v，5). 是

i have this code that converts integers into roman numerals i need to add a function that compares an integer with a roman numeral input and show if it's try or false, for example: roman(v,5). true

toroman(0).
toroman(N) :- N < 4, put("I"), M is N - 1, toroman(M).
toroman(N) :- N = 4, put("I"), put("V").
toroman(N) :- N = 5, put("V").
toroman(N) :- N < 9, put("V"), M is N - 5, toroman(M).
toroman(N) :- N = 9, put("I"), put("X").
toroman(N) :- N < 40, put("X"), M is N - 10, toroman(M).
toroman(N) :- N < 50, put("X"), put("L"), M is N - 40, toroman(M).
toroman(N) :- N < 90, put("L"), M is N - 50, toroman(M).
toroman(N) :- N < 100, put("X"), put("C"), M is N - 90, toroman(M).
toroman(N) :- N < 400, put("C"), M is N - 100, toroman(M).
toroman(N) :- N < 500, put("C"), put("D"), M is N - 400, toroman(M).
toroman(N) :- N < 900, put("D"), put("D"), M is N - 500, toroman(M).
toroman(N) :- N < 1000, put("C"), put("M"), M is N - 900, toroman(M).
toroman(N) :- N < 4000, put("M"), M is N - 1000, toroman(M).



roman(N) :- toroman(N).

推荐答案

尝试以不同的方式表述问题:编写语法( dcg )，以关联整数和表示罗马数字的字符列表.这是一个开始:

Try to formulate the problem differently: Write a grammar (dcg) to relate an integer and a list of characters denoting roman numerals. Here is a start:

:- use_module(library(clpfd)).

roman(0) --> "".
roman(N0) --> "I", { 1 #=< N0, N0 #=< 3, N1 #= N0-1}, roman(N1).

您可以像这样使用它:

?- phrase(roman(3), L).
L = "III" ;
false.

或

?- phrase(roman(N), "II").
N = 2 ;
false.

或者，如果您不知道要问什么，只需问一个最普遍的问题:

or, if you don't know what to ask, simply ask the most general question:

?- phrase(roman(N), L).
N = 0,
L = [] ;
N = 1,
L = "I" ;
N = 2,
L = "II" ;
N = 3,
L = "III" ;
false.

要像L = "III"一样紧凑地获取答案，请使用:- set_prolog_flag(double_quotes,chars).参见此答案以了解更多信息.

To get answers compactly like L = "III", use :- set_prolog_flag(double_quotes,chars). See this answer for more.

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