小弟好奇_在ruby中是什么class，便做了个实验，打开irb，输入_.class返回的是NilClass，再输入一次_.class返回的就是Class了，这是为什么? 我的版本是irb 0.95，ruby 1.87
光阴似箭催人老，日月如移越少年。
After testing, I found that "_" should save the content of the last standard output of irb. Of course, since it is standard output, it does not include exception information.
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After testing, I found that "_" should save the content of the last standard output of irb. Of course, since it is standard output, it does not include exception information.