计算器 [英] Calculator
问题描述
您好，
我想制作一个计算器，我可以用一个单词给出输入。 for
例如：（15 * 3）/（2 + 3）
我认为我最常读的是一个字符串，然后在不同的部分分享
进行计算。但我现在不知道如何开始。可以有人
帮助我。
先谢谢。
Hello,
I wanna make a calculator where i can give the input in one word. for
example : (15*3) / (2+3)
I think i most read this in as a string and then share it in different parts
to do the calculation. But i don''t now how tho start with it. Can somebody
help me.
Thanks in advanced.
推荐答案
Flipke写道：
Flipke wrote:
你好，
我想制作一个计算器，我可以用一个单词给出输入。对于
例如：（15 * 3）/（2 + 3）
我想我最多在一个字符串中读到这个，然后在
不同的部分分享它来进行计算。但我现在不知道如何开始。可以
有人帮助我。
先谢谢。
Hello,
I wanna make a calculator where i can give the input in one word. for
example : (15*3) / (2+3)
I think i most read this in as a string and then share it in different parts to do the calculation. But i don''t now how tho start with it. Can somebody help me.
Thanks in advanced.
你可能会问你的助教/教授一些提示
开始做作业。
你也可以google forrecursive descent parser，这是一个
解决此类问题的标准方法。 K& R还有一个
计算器，但是他们的示例程序使用RPN
。
-David
You might ask your teaching assistant/professor for some hints on how
to get started on your homework.
You could also google for "recursive descent parser", that being a
standard approach for this sort of problem. K&R also has an
calculator, though
their example program uses RPN.
-David
" Flipke" <是********** @ hotmail.com>在留言中写道
新闻：ld ******************** @ scarlet.biz ...
"Flipke" <am**********@hotmail.com> wrote in message
news:ld********************@scarlet.biz...
你好，
我想制作一个计算器，我可以用一个单词给出输入。对于
例如：（15 * 3）/（2 + 3）
我想我最多在一个字符串中读到这个，然后在不同的
部分分享它来做计算。
是的，'分而治之'是编程中的一个好习惯。
但我现在不知道如何开始。
首先，如你所说，阅读输入。下一步
将其解析为有意义的段（例如（15 * 3），
15等）。你需要跟踪括号
才能实现
算术运算的正确优先级。递归方法是解决此类问题的最常见方法。
有人可以帮助我。
Hello,
I wanna make a calculator where i can give the input in one word. for
example : (15*3) / (2+3)
I think i most read this in as a string and then share it in different
parts
to do the calculation.
Yes, ''divide and conquer'' is a good practice in programming.
But i don''t now how tho start with it.
First, as you said, read the input. The next step
is to parse it into meaningful segments (e.g. (15 * 3),
15, etc.). You''ll need to keep track of the parentheses
in order to implement the correct precedence of the
arithmetic operations. A recursive approach is the most
common approach to this kind of problem.
Can somebody
help me.
是的，但我们需要一些东西来帮助你。没人会为你写b
。显示您最佳尝试的代码，并且
询问具体问题。
-Mike
Yes, but we need something to help you with. Nobody will
write it for you. Show the code of your best attempt, and
ask specific questions.
-Mike
Flipke写道：
你好，
我想做一个计算器，我可以用一个单词给出输入。对于
例如：（15 * 3）/（2 + 3）
我想我最多以字符串形式阅读它，然后在不同的部分分享它来进行计算。但我现在不知道如何开始。有人可以帮助我。
先谢谢。
Hello,
I wanna make a calculator where i can give the input in one word. for
example : (15*3) / (2+3)
I think i most read this in as a string and then share it in different parts
to do the calculation. But i don''t now how tho start with it. Can somebody
help me.
Thanks in advanced.
看看Kruse，数据结构与程序设计 ;。他展示了如何开发一个简单的公式评估器。 IIRC他使用的是解析树而不是递归下降的b $ b。他原来的版本使用的是Pascal，但是那个很接近
足以让C翻译。或者你可能会看一个更新的版本 -
我认为他已经停止了不可避免的战斗，现在使用C或C ++作为他的
插图语言。
-
Julian V. Noble
物理荣誉教授
jv*@lessspamformother.virginia.edu
^^^^^^^^^^^^^^^^^^
http://galileo.phys.virginia.edu/~jvn/
因为从来没有哲学家能耐心地忍受
牙痛。
- Wm。莎士比亚，很多阿多无所事事。法案诉Sc。 1.
Have a look at Kruse, "Data Structures and Program Design". He shows how
to develop a simple formula evaluator. IIRC he uses a parse tree rather
than recursive descent. His original version used Pascal, but that''s close
enough to C to translate. Or you might look at a more recent edition--
I think he has ceased fighting the inevitable and now uses C or C++ as his
illustration language.
--
Julian V. Noble
Professor Emeritus of Physics
jv*@lessspamformother.virginia.edu
^^^^^^^^^^^^^^^^^^
http://galileo.phys.virginia.edu/~jvn/
"For there was never yet philosopher that could endure the
toothache patiently."
-- Wm. Shakespeare, Much Ado about Nothing. Act v. Sc. 1.
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