Getting Started with Python

First, define variables

print (' Hello World \ n ')

Defining Variables
name= ' Tambaoliang ' #定义字符串一定加 '
age=28

quotation marks use
words= "I ' m Tambaoliang" #字符串里有 ', Outside with "" 
words2= ' You ' are very handsome ' #字符串里有 ', outside with ' 
words3= ' i ' m shanbl,i Love "python" "#字符串既有" and " ", outside with ' or  ' ""

"' Three single quotes to annotate code '

Enter and assign a value
name = input (' Please enter your name: ') #输入内容并将值赋予变量

View Variable Types
type (name)
type (age)

Second, List

Define a list
stus=[' Tambaoliang ', ' Wongduan earthquake ', ' Zhou Yifan ']#定义一个列表, subscript starting from 0

Increase
Stus.append (' Jangchul ')#append在列表末尾增加一个元素
Stus.insert (0, ' ya men ')#inset在指定为增加元素

Delete
Stus.pop (2)#删除指定位置
Stus.remove (' Jangchul ')#删除指定元素
Del Stus[1]#删除指定位置
Stus.clear ()#清空整个list

Modify
stus[1]= ' er sister '#直接通过下标定位修改

Check
Print (Stus[1])
Print (Stus[-1])#下标写-1 Take the last element
Stus.count (' two sisters ')#统计出现的次数
Stus.index (' two sisters ')#返回查询元素第一个出现的下标, if the element does not exist, it will be an error

Sort
Stus.reverse ()#反转列表
nums=[1,3,9,22,55,77,2,5,]
Nums.sort ()#升序
Nums.sort (Reverse=true)#降序

Merging
stus2=[' AA ', ' BB ']
Stus.extend (STUS2)#把stus2合并到stus
Stus3=stus+stus2#合并两个list

three-dimensional arrays
My =[
[1,2,3,4],
[' Name ', ' age ', ' sex ', ' haha ', [' A ', ' B ', ' C ', ' d '],
888,
[x]
]
My ([1],[4],[0])#取a
My.insert ([1][4][3]) #取到字母d
My[1][4].append (' e ') #定位到列表 and add e
my[1][2]= ' gender '   If Username in stus         # Determines whether a variable is in the list
if username  not in stus     #判断某个变量是否不在列表中
Print (len (my))                   #查看变量的元素个数, also the length

Iii. Conditions of Judgment

< Span style= "font-size:13px" > python conditional only if elif else

a=input (' Enter the value of a: ')
b=input (' please enter the value of B: ')

if a==b:
    print (' a==b ')
elif a<b:
    print (' a<b ')

#elif ...   #可以有无限多个判断

else:        #其余情况 without conditions
    print (' A>b ' )

#if can be nested if

Four, while loop

Count=1
While count<=10: #while需要自己定义初始值, step, end value　
Print (' Hello this is the first ' +count+ ')
Count=count+1
Else #正常循环完, perform else

V. FOR loop

Import Random
Num=random.randint (1,100)

For I in range (7):#range是多少, just loop a few times, variable arbitrarily, don't need to define the initial value, starting from 1
Guss = input (' Please enter a number within 100: ')
Guss = Int (Guss)
If Guss==num:
Print (' Congratulations guessed ')
Break#break立即结束循环当前跳出, just jump 1 levels.
Elif Guss>num:
Print (' Guess big ')
Continue #continue跳出本次循环, proceed to the next
else:
Print (' Guess small ')
Continue
Count+=1

else: #正常执行完, perform else
Print (' Sorry times out ')

Print (' Game over! ')

Six, string formatting

Import datetime
user= ' Tambaoliang '
today =datetime.datetime.today () #date类型
today = str (today) #转换为str 

 msg = ' welcome ' +user+ ' Today's date is ' +today  #通过 + stitching string
Print (msg)

print (type user )
print (Today )

method Two: Pass the% pre-defined variable value

 import datetime  
 user= ' Tambaoliang '  
 today = Datetime.datetime.today () #date类型  
 
 age =18  
 score=99.96999  
 
 msg = ' Welcome%s login, today's date is%s '% (user,today) #%s placeholder, string type, can also be substituted for other types, Magnum   
 MSG2 = ' your age is%d, your score is%.2f '% (age,score )  #%d integer placeholder,%f floating-point placeholder,%.2f means reserved two decimal places   
 
 print (Round (score,2))  #round保留几位小数 
   

Vii. Other

name=input (' Please enter name: ')
age=input (' Age: ') #input输入内容默认为str 
Age=int (age) #转换为int 

Import Random
Num=random.randint (1,100) #使用random生成随机数

elif score>80 and score==80: #并且 connected with  and
if sex== ' male ' or sex== ' female ': #或者 connected with or 

#% can be used as escape character

Count+=1
Count-=1
Count*=1
Count/=1

Getting Started with Python