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Hello everyone , I'm cabbage . Because of the needs of the project , Studying recently Python The reptiles of . This one is about Python The basic knowledge of , It is also an introductory knowledge point for learning reptiles ！ If you get something after reading the article , You can support bloggers three times in a row ~, Hee hee .

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List of articles

• One 、 Preface
• Two 、 notes
• 3、 ... and 、 Variable
• Four 、 identifier
• 5、 ... and 、 keyword
• 6、 ... and 、 Basic data type
• • 1、Number Numerical type
  • 2、 Boolean type
  • 3、 String type
• 7、 ... and 、 Advanced data types
• • 1、 list
  • 2、 Tuples
  • 3、 Dictionaries
• 8、 ... and 、 View data type

One 、 Preface

• I will finish my study during the summer vacation Python Crawler video , From entry to project practice , One step at a time , And will continue to update Python Crawler column . Welcome interested partners to discuss relevant knowledge with you , For the mistakes in the article , Welcome to correct ！

Two 、 notes

• In our coding process , Because it takes a long time 、 Forget quickly 、 Complex code logic and other reasons , We can add comments as appropriate , To help yourself and other coders understand . therefore , Study Python It is very necessary to comment on , We should get into the habit of writing annotated code ！

• Like most programming languages ,Python There are two notes ： Single-line comments and Multiline comment .

• Single-line comments : With # start ,# Everything on the right is for illustration , It's not really a program to execute , To assist in explaining .

• Multiline comment : With ‘’‘ Start , And ‘’’ end , Call it a multiline comment .

# Single-line comments , Explain the code 
print(' I want to pass subject one ')
''' Multiline comment Don't panic , Don't panic , There is moonlight under the sun . '''

3、 ... and 、 Variable

• Basic grammar : Variable name = A variable's value
• Variables are used to store data , You can change the value of a variable

question = " What songs do you like ？"
message = " a sunny day "
img = "https://item.jd.com/10046693874903.html"
print(question)
print(message)
print(img)

Running results ：

Four 、 identifier

• In computer programming languages , Identifier is the name used by the user when programming , Used to give variables 、 Constant 、 function 、 Statement block and so on
• Identifiers are made up of letters 、 Underline and numbers make up , And the number can't start
• Case sensitive
• Cannot use keyword

Picture in the following figure X Is an example of nonstandard identifiers ：

5、 ... and 、 keyword

• When talking about symbols , We talked about not using keywords , that Python What are the keywords in ？ Let's have a look ：

FalseNonefromTrueandglobalasassertifbreakclassimportcontinuedefindelelifiselseexceptlambdafinallyfornonlocalnotorpassraisereturntrywhilewithyield

6、 ... and 、 Basic data type

• Because it is a learning reptile , So learn the data types we need , Let's briefly introduce Python What are the data types , And simply understand their basic grammar .

1、Number Numerical type

# Number value type 
# int
money = 20
# float
value = 20.5

2、 Boolean type

# boolean Boolean type 
gender = True
sex = False

3、 String type

# string character string 
message = ' I'm a string '
information = ' strand '
# Nesting uses 
print("' I am a single quotation mark '")
print('" I am a double quotation mark "')

Running results ：

It should be noted that , When there is a need , Single quotation marks and double quotation marks can be nested ~

7、 ... and 、 Advanced data types

• Like I said before , This article begins with a brief introduction to the basic use of grammar , For in-depth learning , In the following article, we will introduce

1、 list

# Application scenarios ： When crawling to multiple data , You can store this data in a list 
book_list = [' Education of love ', ' Journey to the west ', ' The romance of The Three Kingdoms ']
object_list = [' Break the vault of heaven ', 123, 3.5, True]
print(book_list)
print(object_list)

Running results ：

2、 Tuples

age_tuple = (18, 19, 20, 21)
print(age_tuple)

Running results ：

3、 Dictionaries

person = {

'name': ' I'm a cabbage ',
'age': 21,
'major': ' Computer science and technology '
}
print(person)

8、 ... and 、 View data type

• stay Python in , Just define a variable , And it has data , Then its type has been determined , The system will automatically identify . That is to say, when using “ Variable has no type , Data has type ”
• If you want to view the data type stored in a variable temporarily , have access to type( Variable name ), To see the data type stored in the variable

age = 21
print(type(age)) # int
name = ' I'm a cabbage '
print(type(name)) # string
score = 98.5
print(type(score)) # float
gender = True
print(type(gender)) # boolean
list_type = ['hello', 'world']
print(type(list_type)) # list list 
tuple_type = (12, 13, 14,)
print(type(tuple_type)) # tuple Tuples 
dict_type = {
'name': ' Cabbage ', 'age': 21}
print(type(dict_type)) # dict Dictionaries 

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Thank you for reading , Progress together , Hee hee ~