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This article mainly introduces how to use the python identifier, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor take you to understand it.

1. The identifier consists of characters, underscores, and numbers, but the first character cannot be a number.

2. Reserved characters cannot be the same as identifiers.

3. Cannot contain special characters such as spaces, @,%, and $.

4. Letters are strictly case sensitive.

Although identifiers can be underlined, identifiers that begin with underscores often have special meanings, so it is not recommended to use identifiers that begin with underscores unless you really want to do so.

Example

For example, the following identification conforms to the law:

Abcd

Abc_d

Abc_3d

IF / / python is case-sensitive, so if is a reserved word, but IF is not, you can use the

The following identifiers are illegal:

3abc / / numbers cannot begin

If / / identifiers cannot be the same as reserved words

@ abc / / identifiers cannot have special characters such as spaces, @,%, and $

Expansion of knowledge points:

Naming specification for Python identifiers

To put it simply, an identifier is a name, as if each of us has our own name, and its main function is to serve as the name of variables, functions, classes, modules, and other objects.

The naming of identifiers in Python is not random, but must follow certain command rules, such as marble platform factory.

Identifiers are made up of characters (AbeliZ and axiz), underscores, and numbers, but the first character cannot be a number.

The identifier cannot be the same as the reserved word in Python. Reserved words are described in more detail in subsequent chapters.

Identifiers in Python cannot contain special characters such as spaces, @,%, and $.

For example, the identifiers listed below are valid:

UserID

Name

Mode12

User_age

The following named identifiers are invalid:

4word # cannot start with a number

Try # try is a reserved word and cannot be used as an identifier

$money # cannot contain special characters

In Python, the letters in identifiers are strictly case-sensitive, that is, if the size and format of two identical words are different, the meanings of multiple representations are completely different. For example, the following three variables are completely independent and unrelated, and they are independent of each other.

Number = 0

Number = 0

NUMBER = 0

In the Python language, identifiers that begin with an underscore have a special meaning, for example:

Identifiers that begin with a single underscore, such as _ width, represent class attributes that cannot be accessed directly and cannot be imported through from...import*

Identifiers that begin with a double underscore, such as _ _ add, represent private members of the class

Identifiers that begin and end with a double underscore, such as _ _ init__, are dedicated identifiers.

Therefore, you should avoid using identifiers that begin with an underscore unless required by a particular scenario.

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