Question

关于Python中元组的问题

代码:
#!/usr/bin/python
zoo = ('wolf', 'elephant', 'penguin')
print 'Number of animals in the zoo is', len(zoo)
new_zoo = ('monkey', 'dolphin', zoo)
print 'Number of animals in the new zoo is', len(new_zoo)

输出
$ python using_tuple.py
Number of animals in the zoo is 3
Number of animals in the new zoo is 3

问题:
Line2 中 Number of animals in the new zoo is 3 这里有点奇怪, 为什么是3不是5 , 'monkey' + 'dolphin'+ zoo 中的3只动物, 应该是5啊, 为什么是3呢?

Answer 1

new_zoo = ('monkey', 'dolphin', zoo) = ('monkey', 'dolphin', ('wolf', 'elephant', 'penguin'))
而不是等于 ('monkey', 'dolphin', 'monkey', 'dolphin', zoo)
所以 len(new_zoo) 还是等于3。只不过它的第三个元素也是个元组罢了。

Answer 2

new_zoo: ('monkey', 'dolphin', ('wolf', 'elephant', 'penguin'))

"zoo tuple" is the 3rd element of "new_zoo"

Answer 3

new_zoo: ('monkey', 'dolphin', ('wolf', 'elephant', 'penguin'))