来自 print(print(print('aaa'))) 的 Python 输出 [英] Python output from print(print(print('aaa')))

问题描述

我不太明白收到的输出:

I don't quite understand output received from:

打印(打印(打印('aaa')))

print(print(print('aaa')))

啊啊

无

无

首先 aaa 是明确的.但我认为第二个打印(aaa)会抛出一个错误，因为变量 aaa 没有定义......

First aaa is clear. But I thought that second print(aaa) will throw an error as variable aaa is not defined...

推荐答案

打印(打印('aaa'))

print(print('aaa'))

外部 print 将接收的参数不是内部 print 打印到标准输出的内容，而是内部 print 返回的内容.而print 函数从不返回任何东西(相当于返回None).这就是您看到此输出的原因.

The outer print will receive as argument not what inner print printed to stdout, but what inner print returned. And print function never returns anything (equivalent to returning None). That's why you see this output.

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