Question

在ruby中的散列上调用each时，您可以像这样将键和值很好地分开：

{ :a => 1, :b => 2, :c => 3 }.each do |key, value| 
  puts "key is #{key} and value is #{value}"
end

=========================

key is :a and value is 1
key is :b and value is 2
key is :c and value is 3
=> {:a=>1, :b=>2, :c=>3}

但是，使用inject时，这似乎不起作用。

{ :a => 1, :b => 2, :c => 3 }.inject(0) do |result, key, value| 
  puts "key is #{key} and value is #{value}"
  result + value
end

=========================

key is [:a, 1] and value is
TypeError: nil can't be coerced into Fixnum

在上面的简化示例中，我并不真正需要密钥，所以我可以只调用hash.values.inject，但假设我需要两个，那么这个可怕的小屋是否有更简洁的方法来做到这一点？

{ :a => 1, :b => 2, :c => 3 }.inject(0) do |result, key_and_value| 
  puts "key is #{key_and_value[0]} and value is #{key_and_value[1]}"
  result + key_and_value[1]
end

Answer 1

看起来你需要：

{ :a => 1, :b => 2, :c => 3 }.inject(0) do |result, (key, value)| 
    puts "key is #{key} and value is #{value}"
    result + value
end

使用inject时可以分离哈希的键和值吗？

1 个答案: