Python learning "2nd": Python data types

numeric types and String types

The 1.bin () function converts decimal into a binary

The 2.OCT () function converts decimal into octal

The 3.hex () function converts decimal into hexadecimal

Hexadecimal representation: 0-9 a B c d E F

4. Characteristics of numeric types:

Only one value can be stored

Once defined, cannot be changed

Direct access

Categories: integers, booleans, floating-point, plural

5. String type

Quotation marks contain string types

s1= ' Hello world ' s= "Hello World"

s2= "" "Hello World" ""

s3= ' Hello World '

Single-lead double-lead no difference

6. Common Operations for strings

Strip () remove whitespace, or remove other characters

Slipt () split, separated by a space by default. can also be split with other characters

Len () Length slice: such as print (X[1:3]) is also Gu Tou regardless of the tail

Print (X[0:5:2]) #0 2 4

Capitalize () Capitalize first letter

Center () Center Display for example: x= ' Hello ' Print (X.center (30, ' # '))

Count (): Count, Gu Tou regardless of the tail, count the number of characters, the space is also counted as a character

EndsWith () at what end

Satrtswith () Start with what

Find () finds the index position of the character, if it is negative, indicates that the lookup failed

Index () indexes

The difference between find () and index (), such as:

　　　　　　

Format () string formatting

1.msg= ' name:{},age:{},sex:{} '

Print (Msg.format (' Haiyan ', 18, female))

2.msg= ' name:{0},age:{1},sex:{0} '

Print (Msg.format (' aaaaaa ', ' bbbbbb '))

3.msg= ' Name:{x},age:{y,sex:{z} '

Print (Msg.format (x= ' Haiyan ', y= ', z= ' women '))

IsDigit () Determine if it is a number

Islower () to determine whether it is all lowercase

Isupper () to determine if it is all uppercase

Lower () convert all to lowercase

Upper () Convert all to uppercase

Isspace () Determine if it is all spaces

Istitle () to determine if it is a title (capitalized in the first letter)

Swapcase () uppercase and lowercase letters flipped

Join () connection

Repalce () Replace

msg= ' Hello Alex '

Print (Msg.replace (' e '), ' A ', 1)

Print (Msg.replace (' e '), ' A ', 2)

Ljust () Align Left

x= ' ABC ' Print (X.ljust (10, ' * '))

Some methods of string formatting and string

1.%s,%d

Example 1:name= ' Egon '

Age=20

Print ("My name is%s my age is%s"% (name,age)) #%s can accept both a string and a number

Print (' My name is%s my age is%d '% (name,age)) #%d can only accept numbers

Example 2: Display of user information

1 while True:2     name=input ("Name:") 3     Age=input ("Age:") 4     sex=input ("Sex:") 5     height=input ("Height:") ) 6     msg= "7              ------------%s Info-----------8              name:%s 9              age:%s10              sex:%s11              height:%s12              ------------------------------         "% (name,name,age,sex,heigth)     print (msg)

The results of the operation are as follows:

2. String methods

# name= ' Egon ' #name =str (' Egon ') # print (type (name)) #优先掌握 # # # # Remove white strip# msg= ' Hello ' # print (msg) # Print ( Msg.strip ()) # remove ' * ' # msg= ' ***hello********* ' # msg=msg.strip (' * ') # print (msg) #移除左边的 # Print (Msg.lstrip (' * ')) #移除右边的 #  Print (Msg.rstrip (' * ')) #用处while true:name=input (' User: '). Strip () Password=input (' Password: '). Strip () if name = = ' Egon ' and password = = ' 123 ': print (' login successfull ') #切分split # info= ' Root:x:0:0::/root:/bin/bash ' # print (info[0 ]+INFO[1]+INFO[2]+INFO[3] # user_l=info.split (': ') # print (user_l[0]) # msg= ' Hello World Egon say Hahah ' # print ( Msg.split ()) #默认以空格作为分隔符 #cmd= ' download|xhp.mov|3000 ' # cmd_l=cmd.split (' | ') # print (cmd_l[1]) # print (cmd_l[0]) # Print (Cmd.split (' | ', 1)) #用处while true:cmd=input (' >>: '). Strip () If Len (cmd ) = = 0:continue Cmd_l=cmd.split () print (' command is:%s ' parameter is:%s '% (Cmd_l[0],cmd_l[1])) #长度len # Print (len (' Hell 123 ')) #索引 # Cut Slices: Tangent substring # msg= ' Hello World ' # print (Msg[1:3]) #1 (Msg[1:4]) #1 2 3# Mastering part oldboy_age=84While True:age=input (' >>: '). Strip () If Len (age) = = 0:continue If Age.isdigit (): Age=int (AG e) Else:print (' must be int ') #startswith, endswith# name= ' ALEX_SB ' # print (Name.endswith (' SB ')) # print (name.starts With (' Alex ')) #replace # name= ' Alex Say:i has one tesla,my name is Alex ' # Print (Name.replace (' Alex ', ' SB ', 1)) # print (' My NA Me is%s My age was%s my sex is%s '% (' Egon ', ' Male ') # print (' My name was {} my age is {} My sex is {} '. Format (' Egon ', 18 , ' Male ') # print (' My name is {0} my age is ' {1} ' my sex is {0}: {2} '. Format (' Egon ', ' Male ') ') # print (' My name is ' {name} my Age was {age} my sex is {sex} '. Format (# sex= ' Male ', # age=18,# name= ' Egon ') # name= ' goee say hello ' # # print (nam E.find (' s ', 1,3)) #顾头不顾尾, not found then return-1 does not error, found the index # # print (Name.index (' s ')) #同上, but could not find error # # print (Name.count (' s ', 1,5)) # Gu Tou Regardless of the end, if you do not specify a range then find all #join# info= ' Root:x:0:0::/root:/bin/bash ' # print (Info.split (': ')) # l=[' root ', ' x ', ' 0 ', ' 0 ', ', '/ Root ', '/bin/bash ']# print (': '. Join (L)) #lower, upper# name= ' EGon ' # print (Name.lower ()) # Print (Name.upper ()) #了解部分 #expandtabs# name= ' Egon\thello ' # print ( Name) # print (Name.expandtabs (1)) #center, ljust,rjust,zfill# name= ' Egon ' # print (Name.center (+, '-')) # print ( Name.ljust (' * ') # print (Name.rjust (+, ' * ')) # print (Name.zfill) #用0填充 #captalize,swapcase,title# name= ' EGon ' # Print (Name.capitalize ()) #首字母大写, remainder of lowercase # print (name.swapcase ()) #大小写翻转 # msg= ' Egon say hi ' # print (Msg.title ()) # Capitalize the first letter of each word # in Python3 num0= ' 4 ' num1=b ' 4 ' #bytesnum2 =u ' 4 ' #unicode, python3 without adding U is unicodenum3= ' four ' #中文数字num4 = ' Ⅳ ' #罗马数字 # isdigt:str,bytes,unicode# print (Num0.isdigit ()) # Print (Num1.isdigit ()) # Print (Num2.isdigit ()) # Print (Num3.isdigit ( ) # Print (Num4.isdigit ()) #isdecimal: str,unicode# num0= ' 4 ' # num1=b ' 4 ' #bytes # num2=u ' 4 ' #unicode, Python3 no need to add U is unicode# num3= ' four ' #中文数字 # num4= ' Ⅳ ' #罗马数字 # print (Num0.isdecimal ()) # # Print (NUM1.) # Print (Num2.isdecimal ()) # Print (Num3.isdecimal ()) # Print (Num4.isdecimal ()) #isnumeric: Str,unicode, Chinese, Roman # num0= ' 4 ' # Num1=b ' 4 ' #bytes # num2=u ' 4 ' #unicode, Python3 no need to add U is unicode# num3= ' four ' #中文数字 # num4= ' Ⅳ ' #罗马数字 # # print (Num0.isnumeric ()) # # print (NUM1) # Print ( Num2.isnumeric ()) # Print (Num3.isnumeric ()) # Print (Num4.isnumeric ()) #is其他 # name= ' egon123 ' # print (Name.isalnum ()) # String consists of letters and numbers # name= ' Asdfasdfa SDF ' # print (Name.isalpha ()) #字符串只由字母组成 # # name= ' asdfor123 ' # print (Name.isidentifier ()) Name= ' Eggon ' Print (Name.islower ()) # Print (Name.isupper ()) # Print (Name.isspace ()) name= ' Egon say ' Print (Name.istitle ( ))

List

First, List

Role: Multiple equipment, multiple hobbies, multiple courses, multiple girlfriends, etc.

Definition: [] can have multiple values of any type, comma separated

The following are common actions for a list:

  1 l=[1,2,3] #l =list ([3]) 2 # Print (Type (l)) 4 #pat1 = = = "Priority" Part 5 # Index: l=[1,2,3,4,5] 6 print (l[0]) 7 # Slices 8 l=[' A ', ' B ', ' C ', ' d ', ' e ', ' F '] 9 # print (L[1:5]) One # print (L[1:5:2]) # print (L[2:5]) # print (l[-1]) 14 1 5 #了解 # Print (l[-1:-4]) # print (l[-4:]) # l=[' A ', ' B ', ' C ', ' d ', ' e ', ' F '] # print (l[-2:]) 21 22 # Append # H obbies=[' play ', ' eat ', ' sleep ', ' study '] # hobbies.append (' Girls ') # print (Hobbies) 26 27 # Delete the hobbies=[' play ', ' E  At ', ' Sleep ', ' study '] # X=hobbies.pop (1) #不是单纯的删除, is to delete and return the deleted element, we can use a variable name to receive the return value of # print (x) to # Print (hobbies) 32 # x=hobbies.pop (0) # Print (x) + # X=hobbies.pop # (0) PNS # Print (x) #队列: First-come-out, queue_l=[], #入队 # que Ue_l.append (' first ') # Queue_l.append (' second ') # Queue_l.append (' third ') # print (queue_l) #出队 # print (Queu E_l.pop (0)) # print (Queue_l.pop (0)) # print (Queue_l.pop (0)) #堆栈: Advanced, last in first out, # l=[] # #入栈 # L.appen D (' first ') # L.append(' second ') # L.append (' third ') # # #出栈 # print (l) # Print (L.pop ()) # Print (L.pop ()) # Print (L.pop ()) 63 6 4 #了解 # del hobbies[1] #单纯的删除 # hobbies.remove (' eat ') #单纯的删除, and is the specified element to remove 67 68 69 # Length # hobbies=[' play ', ' eat ' , ' Sleep ', ' study '] # print (len (hobbies)) 72 73 # contains in # hobbies=[' play ', ' eat ', ' sleep ', ' study '] # print (' Sleep ' In hobbies) * msg= ' Hello World Egon ' "# Print (' Egon ' in msg) * * #pat2 = = =" Master part of the hobbies=[' play ', ' eat ', ' Sleep ', ' study ', ' eat ', ' eat '] # Hobbies.insert (1, ' Walk ') # Hobbies.insert (1,[' walk1 ', ' walk2 ', ' Walk3 ']) # print ( Hobbies) Hobbies.count # print (' eat ') # print (Hobbies) # hobbies.extend ([' Walk1 ', ' walk2 ', ' Walk3 ']) # Prin T (Hobbies) hobbies=[' play ', ' eat ', ' sleep ', ' study ', ' eat ', ' eat '] (Hobbies.index (' eat ')) 94-#pat3 = = = " Learn part of the hobbies=[' play ', ' eat ', ' sleep ', ' study ', ' eat ', ' eat '] 98 # hobbies.clear () # Print (Hobbies) # 101 # l=hobbies.co PY () 102 # Print (L) 103 104 # L=[1,2,3,4,5]105 # L.reverse () 106 # Print (l) 107 108 l=[100,9,-2,11,32]109 l.sort (reverse=true) print (L) 

Python learns the 2nd article: Python data type