a = [[1,2,3], [4,5,6], [7,8,9]]
a.each {|v| print v}
结果：
[1,2,3][4,5,6][7,8,9]
a.each {|v| puts v}
结果：
1
2
3
4
5
6
7
8
9
我知道print和puts差别
print打印出来，我可以了解！
但是 puts 打印出来，我不明白。
如果puts是会换行，如果换行应该打赢成这样吧！：
[1,2,3]
[4,5,6]
[7,8,9]
还有一个问题就是：
Ruby
a.each {|v| puts v[0]} # 1,4,7
Python
for i in a:
print i[0] # [1,2,3]
each和for都一样，我已经测试了。但是我搞不清楚，为什么ruby结果是147而不是[1，2，3]呢？
谢谢解答！
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Correct to the first one, why is it not what you said, but the following:
[1,2,3]
[4,5,6]
[7,8,9]
First of all, let me ask you why you said this? Can you give yourself the answer?
puts outputs the content and then wraps it. Since one dimension is wrapped, why don't you wrap it in two dimensions?
2
a After adjusting each, there is a 1-dimensional array in the loop. Each time, the first element (subscript 0) in the one-dimensional array is taken, which is of course 1, 4, 7