Question

我写了一个基本的计算程序。该程序对某些输入运行正常，而为其他输入提供TypeError。我无法弄清楚这种不可预测的行为背后的原因。这是我的代码 -

class Conversion
I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000
result = 0
puts "enter the string"
input = gets.chomp.upcase
temp = input.split(//)
for i in temp do
    case i
        when 'M'
            result = result + M
        when 'D'
            result = result + D
        when 'C'
            result = result + C
        when 'L'
            result = result + L
        when 'X'
            result = result + X
        when 'V'
            result = result + V
        when 'I'
            result = result + I
        end
   end
   puts result
end

错误日志为 -

assignment1.rb：22：在+': Array can't be coerced into Fixnum (TypeError) from assignment1.rb:22:in块中' from assignment1.rb：7：in each' from assignment1.rb:7:in' 来自assignment1.rb：1：在''
中

现在，当我提供像mxcd，dcm，lxv等输入时，它可以正常工作。但对于像xvi，ivx，icd这样的输入，它会产生TypeError。

需要帮助。提前谢谢。

Answer 1

I = 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000

被解释为

I = ( 1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000)

导致

I = [1, V = 5, X = 10, L = 50, C = 100, D = 500, M = 1000]

用逗号代替分号。

Answer 2

为什么不使用哈希而不是像这样的一堆常量：

class Conversion
  CONVERSIONS ={'I' => 1, 'V' => 5, 'X' => 10, 'L' => 50, 'C' => 100, 'D' => 500, 'M' => 1000}.freeze
  puts "enter the string"
  gets.chomp.upcase.split(//).inject(0) { |sum, i| sum + CONVERSIONS[i].to_i }
end

数组无法强制转换为Fixnum（TypeError）

2 个答案: