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