Ruby/Rails - 获取数组中的最后两个值

Question

@numbers = [ 1, 2, 3, 4, 5, 6, 7, 8 ]

@numbers.last 会给我8

我需要抓住最后两个记录.到目前为止,我已经尝试了这个,但它抛出了NoMethodError:

@numbers.last - 1

Answer 1

last 采取论点:

@numbers = [ 1, 2, 3, 4, 5, 6, 7, 8 ]
@numbers.last(2) # => [7,8]

如果要删除最后两项:

@numbers.pop(2) #=> [7, 8]
p @numbers #=> [1, 2, 3, 4, 5, 6]

Answer 2

数组是使用[]not 定义的{}.您可以使用负索引和范围来执行您想要的操作:

>> @numbers = [ 1, 2, 3, 4, 5, 6, 7, 8 ] #=> [1, 2, 3, 4, 5, 6, 7, 8]
>> @numbers.last #=> 8
>> @numbers[-2..-1] #=> [7, 8]