x=10deffoo():x+=1print(x)foo()Traceback(most recent call last):File"D:/程序代码/Python/QRcode_Make/test.py",line5,in<module>foo()File"D:/程序代码/Python/QRcode_Make/test.py",line3,infoo x+=1UnboundLocalError:local variable'x'referenced before assignment 上述代码出错的原因是:局部变量x没有初始值,外部变量X不能引入到内部...
continue语句被用来告诉Python跳过当前循环块中的剩余语句,然后继续进行下一轮循环。 5、pass 语句 Python pass是空语句,是为了保持程序结构的完整性。 pass 不做任何事情,一般用做占位语句 四、列表、元组、字典、集合 1、列表 创建列表 names = ['张三',"李四",'王五'] 通过下标访问列表中的元素,下标从0开始...
Strings can beconcatenatedto build longer strings using the plus sign and also they can bemultipliedby a number, which results in the continuous repetition of the string as many times as the number indicates. Also, if we want to find out thelengthof the string, we simply have to use thelen...
Steps to convert bytes to a string using thedecode()function in Python: Find the bytes that you want to convert Call thedecode()method on the byte string and pass the appropriate encoding as an argument. Assign the decoded string to a variable. ...
变量名应该遵循一定的命名约定,采用驼峰命名法或下划线命名法:驼峰命名法指的是将每个单词的首字母大写,单词之间不使用下划线,例如myVariableName;下划线命名法指的是使用小写字母和下划线来分隔单词,例如my_variable_name。在Python中,推荐使用下划线命名法(也称为蛇形命名法) 变量名只能包含字母、数字和下划线_,不能以...
local scope will change global variable due to same memory used input: importnumpyasnpdeftest(a):a[0]=np.nanm=[1,2,3]test(m)print(m) output: [nan, 2, 3] Note python has this really weird error if you define local variable in a function same name as the global variable, program...
We have to define a function that will accept string argument and print it. Here, we will learnhow to pass string value to the function? Example Consider the below example without sample input and output: Input: str = "Hello world" ...
main.py:9: error: Incompatible typesinassignment (expression hastype"float", variable hastype"int") main.py:14: error: Argument1to"multiply"has incompatibletype"Set[str]"; expected"Sequence[Union[int, float]]"Found2errorsin1file (checked1source file) ...
Inside the curly braces{},alignis a variable that is part of the format specifier and its value changes with each iteration of the loop. The10following{align}is the field width for the formatted string. Depending on the value ofalign, the string ‘hello’ is aligned to the left, center,...
type(variable) 返回输入的变量类型,如果变量是字典就返回字典类型 key in dict 判断键是否存在于字典中 字典推导式 构造函数 dict() 直接从键值对元组列表中构建字典。如果有固定的模式,列表推导式指定特定的键值对: >>> dict([('sape',4139), ('guido',4127), ('jack',4098)]) {'sape':4139,'jack'...