如何在迭代数组时使用 Array # delete？

我有一个数组，我想迭代和删除一些元素。这是不工作的:

a = [1, 2, 3, 4, 5]
a.each do |x|
next if x < 3
a.delete x
# do something with x
end
a #=> [1, 2, 4]

我希望 a是 [1, 2]。我怎样才能绕过这个问题？

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最佳答案

a.delete_if { |x| x >= 3 }

See method documentation here

Update:

You can handle x in the block:

a.delete_if do |element|
if element >= 3
do_something_with(element)
true # Make sure the if statement returns true, so it gets marked for deletion
end
end

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I asked this question not long ago.

Deleting While Iterating in Ruby?

It's not working because Ruby exits the .each loop when attempting to delete something. If you simply want to delete things from the array, delete_if will work, but if you want more control, the solution I have in that thread works, though it's kind of ugly.

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You don't have to delete from the array, you can filter it so:

a = [1, 2, 3, 4, 5]


b = a.select {|x| x < 3}


puts b.inspect # => [1,2]


b.each {|i| puts i} # do something to each here

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Another way to do it is using reject!, which is arguably clearer since it has a ! which means "this will change the array". The only difference is that reject! will return nil if no changes were made.

a.delete_if {|x| x >= 3 }

a.reject! {|x| x >= 3 }

will both work fine.