Ruby/Rails - 获取数组中的最后两个值
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Ruby/Rails - Get the last two values in an array
提问by fulvio
@numbers = [ 1, 2, 3, 4, 5, 6, 7, 8 ]
@numbers = [ 1, 2, 3, 4, 5, 6, 7, 8 ]
@numbers.lastwill give me 8
@numbers.last会给我 8
I need to grab the last two records. So far I've tried this, however it throws a NoMethodError:
我需要获取最后两个记录。到目前为止，我已经尝试过这个，但是它抛出了一个NoMethodError：
@numbers.last - 1
@numbers.last - 1
回答by steenslag
lasttakes an argument:
last接受一个论点：
@numbers = [ 1, 2, 3, 4, 5, 6, 7, 8 ]
@numbers.last(2) # => [7,8]
If you want to remove the last two items:
如果要删除最后两项：
@numbers.pop(2) #=> [7, 8]
p @numbers #=> [1, 2, 3, 4, 5, 6]
回答by Michael Kohl
Arrays are defined using []not {}. You can use negative indices and ranges to do what you want:
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]
