importrandom You can avoid the error by making the import of random like this: fromrandomimport* Or, you can leave the ordinary import statement and fully qualify thechoiceidentifier with therandommodule name, like this: speed=[random.choice([-2,2]),random.choice([-2,2])] As always, I...
2.9术语表 变量(variable):引用一个值的名字。 赋值语句(assignment statement):将一个值赋值给变量的语句。 状态图(state diagram):用来展示一些变量以及其值的图示。--调试的好帮手 关键字(keyword):编译器或解释器保留的词,用于解析程序;变量名不能使用关键字,如if,def,while等。 操作数(operand):操作符所操...
price in products: unique_price_set.add(price) return len(unique_price_set) products = [ (143121312, 100), (432314553, 30), (32421912367, 150), (937153201, 30) ] print('number of unique price is: {}'.format(find_unique_price_using_set(products))) # 输出 number of unique ...
13) Using an augmented assignment operator on a new variable. (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 ...
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...
You can use the del statement to remove a variable, which means the reference from the name to the value is deleted, and trying to use the variable causes an error. Deleted variables can be reassigned to later as normal. >>> foo = "a string" ...
print("Variable x is not defined") except: print("Something else went wrong") Try it Yourself » See more Error types in ourPython Built-in Exceptions Reference. Else You can use theelsekeyword to define a block of code to be executed if no errors were raised: ...
body包含函数执行的语句(statement) 语句需要缩进(由 Code Style Guide 决定) 当语句不再缩进,函数部分结束 一般会使用return语句,来让函数返回其结果,但不是必须的 Hint 类似于用一个=来对多个变量赋值,函数的返回结果也可以不止一个(用逗号,分隔)
PYTHONHASHSEED If this variable is set to "random", a random value is used to seed the hashes of str, bytes and datetime objects. If PYTHONHASHSEED is set to an integer value, it is used as a fixed seed for generating the hash() of the types covered by the hash randomization. Its...
Python编程的语法规范 python语言的语法规则,目录一、概述二、变量1)变量定义2)定义变量的规则3)变量命名规范4)变量类型转换三、注释1)单行注释2)多行注释1、单引号(''')注释2、双引号(""")注释四、运算符1)算术运算符2)关系运算符3)赋值运算符4)逻辑运算符5