Question

我正在编写一个小型Ruby算法，仅在以“1”结尾的值上抛出上述错误，如“21”，“31”，“41”。

success = []
(1..9_999_999).each do |num|
  num_s = num.to_s.split("")
    if num_s.inject(0){ |memo, val| memo += (1..val.to_i).inject(&:*) } == num
      success << []
    end
end

奇怪的是，主代码本身没有错误：

["2", "1"].inject(0){ |memo, val| memo += (1..val.to_i).inject(&:*) } #-> 3

根据错误，我认为可能会出现问题：

(1.."1".to_i).inject(&:*) #-> 1

但是没有......我很困惑。

Answer 1

>> ["1", "0"].inject(0){ |memo, val| memo += (1..val.to_i).inject(&:*) } #-> 3
TypeError: nil can't be coerced into Fixnum
        from (irb):2:in `+'
        from (irb):2:in `block in irb_binding'
        from (irb):2:in `each'
        from (irb):2:in `inject'
        from (irb):2
        from C:/Ruby200-x64/bin/irb:12:in `<main>'

发生以上错误是因为：(1..0).inject(&:*)返回nil。

>> (1..0).inject(&:*)
=> nil
>> 0 * (1..0).inject(&:*)
TypeError: nil can't be coerced into Fixnum
        from (irb):4:in `*'
        from (irb):4
        from C:/Ruby200-x64/bin/irb:12:in `<main>'

“nil无法强制进入Fixnum”意外错误

1 个答案: