0 Basic python-3.3 Identifiers

1. Composition of identifiers

1) There are numbers, underscores, English letter composition

2) The first character can only be a letter or an underscore

3) Case Sensitive

Identifiers are typically variable names, method names, class names, and so on

2. Keywords

Python has a series of keywords, if you do not know a word is not, you can use Iskeyword () This method to test

3. Built-in

1) can be used as a system reserved word

2) can be used as a global variable

3) interpreter is automatically imported before Python starts

4. Dedicated underline

1) _xxx do not import from module import *

2) _xxx_ System definition Name

3) Private variables in the _xxx class

Note: Double underlines have special meanings for python, such as __ini__, which represents the initialization method for a class, followed by a number of detailed expansion

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0 Basic python-3.3 Identifiers