Python cmp() 函数

Question

您好，我正在尝试使用 cmp() 函数比较 python 中的两个元组但是出现以下错误：

NameError: 名称 'cmp' 未定义

我的代码：

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

Answer 1

cmp function is only in Python 2.x. As mentioned in the official Python documentation:

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 cmp 等价于：

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

注意：您的元组（myStupidTup 和 mySmartTup）不支持比较。如果你运行你会得到一个TypeError：TypeError: '>' not supported between instances of 'str' and 'int'

Python cmp() 函数

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