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# Author：henry
# Time：2020/5/19 13:47
# Project：2020.05.18python grammar
# email：[email protected]
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# Python How to execute ：
# 1.cmd Execution of terminal commands ：python py Path to file
# 2.Pycharm In file , Right click the blank space to execute
# 3.Pycharm in , Click Run to execute
# pip command ： Online installation of third-party packages , Manage third party packages
# 1. Installation package ：pip install Library name
# 2. Uninstall package ：pip uninstall Library name
# 3. Upgrade package ：pip install -U Library name
# 4. List installed packages ：pip list
# 5. View the current pip Version of ：pip --version
# 6. Generate requirements.txt：pip freeze > requirements.txt
# 7. install requirements.txt：pip install -r requirements.txt
# python Basic syntax ：
# Include indent , Line break , alignment , notes , Output
# 1. Line break ： Each line does only one thing , Include \n Line break
# print(' Today is the first 30 First class of phase \n Write code \n Write the code ') # \n Line break
# 2. notes ： explain
# # Represents a single line comment Shortcut key ：ctrl + /
# Multiline comment Three quotes （ Include single and double quotes ）
'''print('hello,world!!')''' # ctrl + B View the source code
"""print('hello,world!!')"""
# 3. Output ：
# print('xxxxxx') Output function
# 4. Variable
# What is a variable ： Is used to identify data , grammar ： Variable name = value （ data ）
# Variable naming conventions ：
# 1. By digital , Letters and underscores make up
# 2. Cannot start with a number
# 3. It can't be a keyword
import keyword # View keywords
print(keyword.kwlist) # Print
# 4. Case sensitive
# Variable （ identifier ）= value / data （ data type ）
'''today = 'hello,wprld!!' # assignment
print(today)''' # Print
# Variable （ identifier ） The naming style of ：
# 1. Underline nomenclature （ Mainly python）：hello_world
# 2. The name of the great hump ：HelloWorld
# 3. Little hump nomenclature ：hellWorld
# python data type
# 1. String type （str）: Include values enclosed in single and double quotation marks
# 2. The number ： Integers （int） There is no decimal point 、 Floating point numbers (float) There's a decimal point
# 3. Boolean value (bool)：True( really )、False( false )
'''is_ten = False
after_ten = True'''
# 4. Get the current data type ：type( data )
'''age = 18
number = 10.5
study = ' Study '
print(type(age)) # Integer types
print(type(number)) # Floating point type
print(type(study))''' # String type
# Homework after class
'''
One 、 The following cannot be used as variables ？
1、find 2、 _num 3、7val 4、add. 5、def
6、pan 7、-print 8、open_file 9、FileName 10、9prints
11、INPUT 12、ls 13、user^name 14、list1 15、str_
16、_888 17、is 18、true 19、none 20、try
The following cannot be used as variables
3、7val（ Cannot start with a number ）、4、add.（ No symbols ）、5、def （ No keywords ）、 7、-print（ Can not be ）
10、9prints、（ Cannot start with a number ）、13、user^name（ No special symbols ）17、is( No keywords )、20、try（ No keywords ）
Two 、 Please describe the naming conventions of variables ,（ Simple questions ）
Variable naming conventions ：
1. Cannot start with a number
2. By digital , Letters and underscores make up
3. Cannot use keyword
4. Be case sensitive
'''
'''
3、 ... and 、python How to add comments
There are two notes ：
1. A single line comment can be made with ：# notes Shortcut keys are ctrl + /
# Single line notes explain
2. Multiline comment ： Three quotes （ Include single and double quotes ）'''
''' This is how you annotate multiple lines , # Three quotation marks （ Single quotation marks ）
Don't use single line comments line by line '''
''' This is how you annotate multiple lines , # Three quotation marks （ Double quotes ）
Don't use single line comments line by line '''
