ruby - WHEN 是否可以检查变量是否属于数组？

Question

我怎么能做这样的事情？还是我需要一直使用 IF？

ar = [["a","b"],["c"],["d","e"]]
x = "b"
case x
when ar[0].include?(x)
  puts "do something"
when ar[1].include?(x)
  puts "do else"
when ar[2].include?(x)
  puts "do a 3rd thing"
end

我正在使用红宝石 1.8.7

Answer 1

这不仅可能，而且很容易。对于常量数组：

#!/usr/bin/ruby1.8

x = "a"
case x
when 'a', 'b'
  puts "do something"    # => do something
when 'c'
  puts "do else"
when 'd', 'e'
  puts "do a 3rd thing"
end

或者，如果数组不是常量：

#!/usr/bin/ruby1.8

ar = [["a","b"],["c"],["d","e"]]
x = 'd'
case x
when *ar[0]
  puts "do something"
when *ar[1]
  puts "do else"
when *ar[2]
  puts "do a 3rd thing"    # => do a 3rd thing
end

Answer 2

你为什么不重组你的代码并做

ar = [["a","b"],["c"],["d","e"]]
x = "b"
i = (0...ar.length).find {|i| ar[i].include?(x)}
case i
    when 0
        puts "do something"
    when 1
        puts "do else"
    when 2
        puts "do a 3rd thing"
end