Python basics 01 and python01

Python basics 01 and python01

Main content:

• Output
• Note
• Identifier
• Variable
• Data Type
• Operator
• Indent

 

Output "Hello, Python"

Output in shell mode

>>> print("Hello,Python")Hello,Python

Annotation method 1. Single line annotation #

Method 2. Multi-line comment... three quotation marks

#print("Hello,Python!")print("Hello,Python!")'''print(hello)print(python)'''

Identifier (name the variable)

Symbol used to mark something

Rule: (1) first letter: letter + underline

a_ba3_a123

Variable

Variable recovery

Python does not need to define data types.

Reclaim variable

>>> a=1>>> a1>>> print(type(a))<class 'int'>>>> a=1.3>>> a1.3>>> print(type(a))<class 'float'>>>> 

+ =

A + = 1

>>> a=1>>> a+=1>>> a2

 

Data Type

Common Python data types:

Number, String, list, tuple, set, and disctionary)

List: []

>>> L[]>>> L=["My","your"]>>> L['My', 'your']>>> L[0]'My'>>> L[1]'your'>>> L[1]="Me">>> L['My', 'Me']

Tuple :() data in the ancestor cannot be modified

>>> t=("My","You")>>> t('My', 'You')>>> t[0]'My'>>> t[1]'You'>>> 

Set

>>> a="dasdsada">>> b="dasdadadddaa">>> sa=set(a)>>> sa{'a', 'd', 's'}>>> sb=set(b)>>> sb{'a', 'd', 's'}>>> sa&sb{'a', 'd', 's'}>>> 

Dictionary {key1: value1, key2: value2}

>>> d={'name':'duxiao','age':'25'}>>> d{'name': 'duxiao', 'age': '25'}

1 >>> d['name']2 'duxiao'3 >>> d['age']4 '25'5 >>> 

Operator

+-*/% Add subtraction, multiplication, division, and remainder

Operator priority mathematical operators are applicable to Python

Do not know the applicability (), change the priority

>>> a=2>>> b=3>>> a+b5>>> a*b6>>> a-b-1>>> a/b0.6666666666666666>>> a%b2>>> b&a2>>> 7+815

Remainder

>>> 10%31

Division not Remainder

>>> 10//33

Priority

>>> 9+5*2-118>>> (9+5)*2-127>>> 

 

Language of indentation forced indent

Beautiful

The same level is in one indentation.

Tips for indent:

Code at the same level is in the same indentation range. The code at the next layer must be indented relative to the code at the previous level. We recommend that you use the tab key to indent the code!

a=10b=9if(a>9):    print(a)    if(b==9):        print(b)elif(a<10):    print("abc")