计算器问题 [英] calculator issue

问题描述

我想设计一个特殊的计算器.. 我遇到了这样的问题: X = 1 +(12 * 4 + 2) 我需要先获取操作数 像这里，我有两个操作数1和(12 * 4 + 2) 我如何区分外+和内+?

I want to design a special calculator .. and I came to a problem like this : X=1+(12*4+2) i need to get number of operands first like here i have two operands 1 and (12*4+2) how could i distinguish between the outer + and the inner one ?

谢谢

这里真是一个了不起的社区.. 从最简单到最困难的答案.. 伙计们，我的问题不是计算器，也不是其他与数学有关的.. 我只是问外在和内在加法，将策略应用在完全不同的事情上.

what an amazing community here .. different answers from easiest to hardest .. guyz my problem is not calculator nor anything else related to math .. I just asked about the outer and inner plus to apply the strategy in a completely different thing .

我正在用Java实现统一算法(就像当您给Prolog解释器两个表达式时所做的一样)

I am implementing unification algorithm in java (just like what Prolog interpreter does when you give it two expressions )

这是算法:

function unify(E1, E2);
    begin
        case
            both E1 and E2 are constants or the empty list:
                if E1 = E2 then return {}
                else return FAIL;
            E1 is a variable:
                if E1 occurs in E2 then return FAIL
                 else return {E2/E1}
            E2 is a variable
                if E2 occurs in E1 then FAIL
                    else return {E1/E2}
            either E1 or E2 are empty then return FAIL
            otherwise:
                begin
                    HE1 := first element of E1;
                    HE2 := first element of E2;
                    SUBS1 := unify(HE1, HE2);
                    if SUBS1 := FAIL then return FAIL;
                    TE1 := apply(SUBS1, rest of E1);
                    TE2 := apply(SUBS1, rest of E2);
                    SUBS2 := unify(TE1, TE2);
                    if SUBS2 = FAIL then return FAIL;
                         else return composition(SUBS1, SUBS2)
                end
            end

现在我的问题是我是否有这样的输入: a(X，Y)= a(b(c，Y)，Z)..

now my question is if I have such input : a(X,Y)=a(b(c,Y),Z)..

如何提取元素的数量(和值)(即第一个Expression的X和Y)

how could I extract number (and values)of the elements (i.e. X and Y for the first Expression )

当我阅读并尝试解决此问题时，我想到了不同的新技术. 像Lexical Analysis，Parsing一样，我对Lexical Alanysis毫无头绪，尽管我知道解析和令牌(以String的方式)，而且我认为这无法解决我的问题.. 我现在正在尝试实现乔伊·亚当斯说的话..我认为这对我的问题很有用..

I have come to different new techniques for me when i read and try to solve this .. like Lexical Analysis,Parsing I have no clue about Lexical Alanysis though I know parsing and tokens (in String manner) moreover i think it's not gonna solve my problem .. I am now trying to implement what Joey Adams said .. I think it's useful to my problem..

这篇散文小伙子的故事...感谢您的帮助

soory for this essay guyz ... appreciate you help

推荐答案

您的问题非常笼统，完整的答案可能需要占用一本书的几章.

Your question is very general, and a complete answer could take up several chapters in a book.

话虽如此，我建议您从谷歌搜索开始，先学习一些术语并了解以下内容:

That being said, I would suggest you start by Googling for some terms and learning about:

标记化和解析(从字符串中提取单个组件.)

Tokenizing and Parsing (extracting the individual components from the string.)

中缀评估(采用一对操作数和一个中间运算符并存储答案)

Infix Evaluation (taking a pair of operands and an intervening operator and storing an answer)

后缀评估(采用一对操作数和后继运算符-尚无道理，但可能需要阅读一会儿.)

Postfix Evaluation (taking a pair of operands and a following operator -- this won't make sense yet, but probably will after you've read a bit.)

..并进一步阅读:

编译器设计

...，当您遇到特定问题时，请继续访问此网站.不要忘记搜索与已经提出的问题类似的答案！

... and as you encounter specific questions, continue to visit this site. Don't forget to search for answers to questions similar to yours that have already been asked!

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