Ruby 计算器 - 哈希存储不正确

Question

所以我将首先写下我是这个网站的新手（今天），以及 Ruby 编程语言（3 天前），所以不要害怕撕裂除了我的代码——我正在努力学习并变得更好。

基本上.. 我正在创建一个控制台计算器，它能够从用户那里读取一个简单的数学问题（或一串数学问题）并求解方程。它不使用操作顺序或任何花哨的东西（还），它基本上可以工作，除了这个我无法弄清楚的奇怪错误。

Userinput = "1 + 2 + 3 - 4"
# First I split the user input into an array of stirngs and then loop over the
# array of strings and depict whether a string is a key or hash (see code below)

# program should store these characters in a hash like so.. 
hash = { nil=>1, "+"=>2, "+"=>3, "-"=>4 }

然后我会使用散列的键来确定我接下来是加减乘除。

一切正常！只是当我用超过 2 个操作（即 1 + 2 - 0 + 3）来解决问题时，程序会随机遗漏一些键和运算符。我一直在尝试不同的示例来搜索模式，但找不到来源。下面我将 post 问题示例及其输出，以及哈希本身，然后是完整的源代码。在此先感谢您的帮助或批评！

示例格式

程序输入（用户提示，用户输入）-- 程序输出（等式之和）—— 执行结束时的散列

示例 1

Type a math problem (ex. 40 / 5): 40 / 5 + 2 - 5 * 5 - 5 * 5 - 100

-450

{nil=>40, "/"=>5, "+"=>2, "-"=>100, "*"=>5}

示例 2

Type a math problem (ex. 40 / 5): 1 + 2 - 0 + 3

4

{nil=>1, "+"=>3, "-"=>0}

示例 3

Type a math problem (ex. 40 / 5): 10 - 5 * 2 + 8 + 2

12

{nil=>10, "-"=>5, "*"=>2, "+"=>2}

源代码：main.rb

=begin
  
  main.rb
  Version 1.0
  Written by Alex Hail - 10/16/2016
 
  Parses a basic, user-entered arithmetic equation and solves it
 
=end

@operationsParser = ""    # global parser
@lastKeyAdded = ""

private
def appointType(sv)
    if sv =~ /\d/
      sv.to_i
    else
      sv
    end
end

private
def operate(operations)
  sum = 0
  operations.each do |k, v|
    if k.nil?
      sum += v
    else
      case k
        when '+' then sum += v
        when '-' then sum -= v
        when '*' then sum = sum * v  
        when '/' then sum = sum / v
        else
      end
     end
   end
   sum
 end

private
def solveEquation
  print "Type a math problem (ex. 40 / 5): "
  userInput = gets.chomp
  
  #array to hold all numbers and their cooresponding operation
  operations = {}   # <== Empty hash
  
  #split the user input via spaces
  @operationsParser = userInput.split(" ")
  
  #convert numbers into numbers store operators in hash ( nil => 40, "/" => 5) -- would be 40 / 5
  @operationsParser.each do |stringValue|
    if appointType(stringValue).is_a? Integer
      

     operations[@lastKeyAdded != "" ? @lastKeyAdded : nil] = appointType(stringValue)
        
    else #appointType will return a string by default
      keyToAdd = appointType(stringValue)
      @lastKeyAdded = keyToAdd
    end
  end
  
  #check if operators(+, *, -, /, or nil) in the keys are valid, if not, error and exit, if so, operate
  operations.each do |k,v|
    case k
      when '+'
      when '-'
      when '*'    
      when '/'
      when nil
      else
        # Exit the program if we have an invalid operator in the hash
        puts "Exiting program with error - Invalid operator used (Only +, -, *, / please)"
        return
    end
  end
  
  sum = operate(operations)
  
  
  puts sum, operations
end

solveEquation

Answer 1

好的，问题出在您选择的数据结构上，根据定义，散列必须始终维护一组唯一键以映射到其值。现在，如果您对使用散列死心塌地，您可以尝试将所有键映射到空数组，然后向其添加数值，然后对其各自数组中的每个值处理该操作（因为您以任何方式忽略了操作顺序）

h = Hash.new([]) #to set the default value of each key to an empty arrary

然后当你处理你的数组时它应该看起来像这样

{nil =>[1], '+' => [1, 2, 3], '-' => [3, 7], '*' => [4, 47], '/' => [3, 5]}

Ruby 计算器 - 哈希存储不正确

Ruby calculator - hash not storing correctly

ruby

hash

calculator