ruby中的for in与each do的区别到底是什么？

Question

如果仅像某些文章说的前者的效率不如后者，那要前者做什么？

Answer 1

Under normal circumstances, try to use each:

1.upto(10).each { |i| puts i }
puts i # NameError: i is undefined

When using for:

for i in 1.upto(10) do
  puts i
end
puts i # print 10

Answer 2

It seems there is no difference, there are usually multiple ways to do one thing in ruby

Answer 3

each do is more efficient. Some programming standards generally do not recommend using for in

Answer 4

This is a matter of programming style. The each loop is a functional style, and the for loop is an imperative style
each is actually a method on an iterable object, accepting a block as a parameter
for is a loop structure implemented in the grammar