标签 ruby
<分区>
对于四元素数组，[4] 返回nil，但[4, 0] 返回一个空数组。
array = [:peanut, :butter, :and, :jelly]
array[4] # => nil
array[4, 0] # => []
array[5] # => nil
array[5, 0] # => nil
为什么 [4, 0] 不像 [5, 0] 那样返回 nil？
Ruby 中数组切片的答案:寻找不合逻辑行为的解释(来自 Rubykoans.com)=> Graphical Explination of WHats Happening
最佳答案
这是一个特例。来自official docs (斜体是我的):
For start and range cases the starting index is just before an element. Additionally, an empty array is returned when the starting index for an element range is at the end of the array.
a = [ "a", "b", "c", "d", "e" ]
# ...
# special cases
a[5] #=> nil
a[6, 1] #=> nil
a[5, 1] #=> []
关于 ruby 切片不为零，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/34979538/