Python data feature escape and operator summary-ten Day

One, assignment operators

The assignment operation assigns the value of a to a value, and the result of the operation is assigned to B.

Second, comparison operators

The result of the comparison operation returns a bool value, True and false, which is typically used to control the process of executing the program, such as the following code:

1 if a = = B:23  execute print (...) 4 5 Else : 6 7 Execute print (----)

Third, logical operation

The logical operation returns the result as a Boolean value, and the control program calculates that the X and C:and are true after the truth; A and B or C:and is false to calculate whether or is true, for true continuation operation, false for false; Not a = B: meaning a! = B

IV. member Operations

Member operations are primarily used to determine whether an element is in a collection of elements:

1A ="ABCDEFG"2b ="a"3 ifBinchA:4     Print("b in the sequence of a")5 Else:6     Print("B is not in the sequence of a")

Data type function: int,str,list,dict,tuple; all have indexing and slicing capabilities.

Number (int)

Python can handle positive and negative integers of any size, but it is actually related to the memory of our computer, on a 32-bit machine, the number of integers is 32 bits, the value range is -2**31~2**31-1, on a 64-bit system, the number of integers is 64 bits, the value range is -2**63~2** 63-1.

1A = 42 Print(A.bit_length ())3Bit_length (self):#real signature unknown; restored from __doc__4         """5 int.bit_length () int6         7 Number of bits necessary to represent self in binary.8 >>> Bin (Panax Notoginseng)9 ' 0b100101 'Ten >>> (PNS). Bit_length () One 6 A         """ -         return0
A = "4"
Page print (int (a)) #讲字符串 "4" converted to an integer 4
16

String (str)

The following are commonly used string functions

1s="abcdef GHG k"2 Print(S.title ())#Convert string to title, output Abcdef Ghg K3  4 Print(S.capitalize ())#capitalize the first letter of the string, output Abcdef GHG k5  6 Print(S.count ('D', 0,len (s)))#calculates the number of occurrences of the substring ' d ' in the parent string, which is found by default in the entire parent string,7  　　　　　　　　　　　　　　　　　  #you can specify the starting position in the following two parameters, where I have specified the lookup in (0,len (s)),8  　　　　　　　　　　　　　　　　　  #where Len (s) stands for string length9  Ten Print(S.startswith ('a'))#to determine if a string starts with something, output true here, One   A Print(S.find ('g', 0,len (s)))#finds the first occurrence of a substring in a string, where it outputs 7, and can also specify a range of positions to search -   - Print(S.upper ())#Convert the string to uppercase, here output abcdef GHG K the   - Print(S.join (['a','b','C']))#use string s to connect list [' A ', ' B ', ' C '] output aabcdef GHG kbabcdef GHG KC -   - Print(S.strip ())#Remove both spaces +   - Print(S.split ())#split the string, return a list here output [' abcdef ', ' GHG ', ' K '] +   A Print(S.replace ('g','G', 1))#Replace, replace all by default, can be set to 1, replace only once, here only once output abcdef GHG k at   - Print(S[0:4])#slice, [0:4] represents the first 4 bits of the string s to be taken out, here output ABCD

Listing (list)

A list is a python built-in data type is a list, an ordered set of elements that can be added and removed at any time.

1l=['a','b','cc', 4]#Define a list2  3L.append (5)#add an element, l=[' A ', ' B ', ' CC ', 4, 5]4  5L.pop ()#remove an element from the tail, l=[' A ', ' B ', ' CC ', 46  7L.remove ('a')#remove ' A ' from the list, l=[' B ', ' CC ', 4]8  9L.extend (['GG','KK'])#Add a list [' GG ', ' KK '], l=[' B ', ' CC ', 4, ' GG ', ' KK 'Ten   OneL.reverse ()#invert a list, l=[' KK ', ' GG ', 4, ' cc ', ' B '] A   - Print(L.count ('KK'))#number of occurrences of an element output 1 -   the Print(L.index ('GG'))#the position where the element appears, Output 1 -   -  forIinchL#looping out list elements -     Print(i) +   - Print(L[0:4:2])#list slices, increment by step 2, Output [' KK ', 4]

Tuple (tuple)

Tuple and list are very similar, but once the tuple initialization can not be modified, the tuple is also ordered, the tuple uses the parentheses identifier; The first-level elements of a tuple cannot be modified, deleted, or child elements can be modified.

1T= ('a','b','b','C')#Define a tuple2  3 Print(T.index ('b'))#index The first occurrence of the element, you can also specify a range to find, here by default in the entire tuple lookup output 14  5 Print(T.count ('b'))#count the number of occurrences of the element, here Output 26  7 Print(Len (t))#output The length of the far group, here output 48  9  forIinchT:Ten     Print(i)#cycle through the tuple data One   A Print(T[1:3])#Slice output (' B ', ' B ')

Dictionary (dict)

Dictionaries are unordered, using key-value (Key-value) storage, with extremely fast lookup speeds.

1D = {'Michael': 95,'Bob': 75,'Tracy': 85}2  3D.get ('Bob')#based on key to get values, if not present returns NONE, here output4  5D.pop ('Bob')#Delete an element by key d={' Michael ': ' Tracy ':6  7d['Jason']=99#new element d={' Michael ': Up, ' Tracy ': ' Jason ': the8  9 Print(Len (d))#Output dictionary length, here output 3Ten   One Print('Jason' inchD#Python3 Remove Has_key, to determine if the key exists in A   -  forIinchD: -     Print(i)#loop default key Output the   -  forIinchD.values ():#looping by value output -     Print(i) -   +  forKvinchD.items ():#cyclic key value output -     Print(K,V)

Python data feature escape and operator summary-ten Day