使用 Prolog 将后缀转换为前缀 [英] Postfix to Prefix Conversion using Prolog

问题描述

谁能帮我在PROLOG中使用堆栈概念编写一个程序，将算术表达式从后缀(反向波兰符号)转换为前缀形式.算术表达式可能包含 4 个算术运算符 +、-、/、* 和一元函数:sin、cos、tan、exp、log 和 sqrt.

Can anyone help me to write a program using stack concept in PROLOG to convert an arithmetic expression from postfix(reverse polish notation) to prefix form. The arithmetic expression may contain the 4 arithmetic operators + , - , / , * and the unary functions : sin, cos, tan, exp, log and sqrt.

推荐答案

append/2 这是一个有用的列表组合器.它以相当一般的方式允许在任意数量的列表之间建立关系.我将在这里只展示基本的，你需要完成你的作业，添加一些细节作为一元函数，定义 isop/1

append/2 it's a useful list combinator. It allows in fairly general way a relation of concatenation among an arbitrary number of lists. I'll show just the basic here, you'll need to complete your assignment adding some detail as unary functions, define isop/1

pos2pre(Pos, Pre) :-
    append([A, B, [O]], Pos), isop(O), A \= [], B \= [],
    pos2pre(A, APre),
    pos2pre(B, BPre),
    !, append([[O], APre, BPre], Pre).
pos2pre([P], [P]).

一个小测试:

?- pos2pre([1,5,*,2,+],X).
X = [+, *, 1, 5, 2].

我认为您应该尝试编写相同的逻辑，但使用 append/3，这将有助于您了解程序的工作原理.

I think you should try to write the same logic but using append/3, that would help you to understand how the procedure works.

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