Python cmp（）函数

Question

您好，我正在尝试使用cmp（）函数比较python中的两个元组 但出现了一个错误，错误如下：

名称错误：未定义名称“cmp”

我的代码：

myStupidTup = ("test",10,"hmm",233,2,"am long string")
mySmartTup = ("test",10,233,2)
print(cmp(myStupidTup, mySmartTup)) 

Answer 1

^{}函数仅在Python 2.x中。如official Python documentation中所述：

The cmp() function should be treated as gone, and the __cmp__() special method is no longer supported. Use __lt__() for sorting, __eq__() with __hash__(), and other rich comparisons as needed. (If you really need the cmp() functionality, you could use the expression (a > b) - (a < b) as the equivalent for cmp(a, b).)

Python 3.x中的^{}等价物是：

def cmp(a, b):
    return (a > b) - (a < b) 

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注意：元组（myStupidTup和mySmartTup）不支持比较。如果运行它，您将得到一个TypeError：TypeError: '>' not supported between instances of 'str' and 'int'