NameError: name 'cmp' is not defined **报错原因:**因为python3.x中cmp函数去掉了,如果需要实现比较功能,那么可引入operator 模块,提供了6个比较运算符。gt lt ge eq le importoperator#首先要导入运算符模块operator#integersx,y = 100,200print("x:",x,", y:",y)print("operator.gt(x,y):", op...
Before using a variable or calling a function, check if it exists to avoid NameError: name is not defined in Python. We can use thein-operator or hasattr() functionin Python to determine if a name is defined. Thein operatorchecks if the value exists in the provided iterable or not in P...
>>> a&b = 1 #不合法 SyntaxError: can't assign to operator >>> 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. >>> a = 1 >>> A Traceback (most recent call last): File "<pyshell#10>", line 1, in <module> A NameError: name 'A' is not defined >>> a ...
python: NameError: name 'cmp' is not defined python 3.4.3 的版本中已经没有cmp函数,被operator模块代替,在交互模式下使用时,需要导入模块。 lt(a,b) 相当于a<b 从第一个数字或字母(ASCII)比大小 le(a,b)相当于a<=b eq(a,b)相当于a==b 字母完全一样,返回True, ne(a,b)相当于a!=b gt(a,...
python3.x中cmp函数会NameError: name 'cmp' is not defined【cmp函数在3.x开始就去掉了,若想实现比较功能可用operator】 **报错原因:**因为python3.x中cmp函数去掉了,如果需要实现比较功能,那么可引入operator 模块。 operator模块,适合任何对象,包含的方法有: operator实例 在python3.x中用cmp函数功能的实例 ...
(Causes “NameError: name 'foobar' is not defined”) Do not assume that variables start off with a value such as 0 or the blank string. A statement with an augmented operator like spam += 1 is equivalent to spam = spam + 1. This means that there must be a value in spam to ...
a,b=(1,2)# leftofbinary operatorforx,yin((1,2),(3,4),(5,6)):# leftofbinary operatorprint(x,y)del a,b # rightofunary statement deff(x):returnx,x**2# rightofunary statement 1.2 命名的元组 命名的元组(namedtuple)与普通元组一样,有相同的表现特征,其添加的功能就是可以根据名称引用元...
Note python has this really weird error if you define local variable in a function same name as the global variable, program will promptUnboundLocalError. child class object overrides parent class methods input: classfruit:defprint(self):print('a')defeat(self):print('b')classapple(fruit):defpr...
# NameError: name 'i' is not defined 现在我们来改写一下它: deffunc(): l= [] foriinrange(4): l.append(lambda:i) returnl 这里func返回了一个包含4个匿名函数的列表,匿名函数返回了i的值,i是函数内部的变量。我们试着在外部调用一下他们: ...
some_unknown_var # Raises a NameError Python支持三元表达式,但是语法和C++不同,使用if else结构,写成: # if can be used as an expression # Equivalent of C's '?:' ternary operator "yahoo!" if 3 > 2 else 2 # => "yahoo!" 上段代码等价于: ...