Description Data Type python

# Python is no need to declare variables. Each variable must be assigned before use variable assignment after the variable will be created. 
# Python3 There are six standard data types: Numbers (digital) String (String) List (list) Tuple (component) Sets (collections) Dictionaries (Dictionary) 

# a Numbers (digital) 
# Python 3 support int, float, bool, complex (complex 
A, B, C, D = 20 is, 5.5, True,. 4 + 3j 
Print (type (A), type (B), type (C), type (D)) 
# The other calculation, here you just write something special 
print (2 // 4) # division (//) get an integer, 
Print (2/4) # division (/) always returned a float 
print (2 ** 5) # multiply Fang 

# string (string) 
S = 'Yes, of He doesn \' t ' 
Print (S, of the type (S), len (S)) 
Print (r'C: \ some \ name') # If you do not want anti slash escape occurs, can be added in front of a string r, represents the original string: 

word1 = 'ILove' 
word2 = 'the Python' 
Print (word1 + word2, word2 *. 3) # + operator may use a string string connections together, or with repeated operator *
print (word2 [0], word2 [5]) # Python strings have two indexing methods, the first from left to right, sequentially increases from 0; the second is from right to left, from the - 1 in order to start to reduce. 
print (word2 [1: 5] ) # slicing string, the substring acquisition period. Two indices separated by a colon, in the form of a variable [head superscript: Tail index], if omitted, no slice. 

# List (list) 
[ 'HIM', 25, 100, 'HER'] A = # similar array 
Print (A) 
Print (A + [. 6,. 7,. 8]) # list also supports operating in series, using the + operator 
a [2: 3] = [ 13] # and cutting a different character, the cutting list may change elements 
Print (a) 


# tuple (tuple) 
# tuple (tuple) and a list of similar, except that the elements of the tuple is not modify. Tuple written in parentheses, separated by commas between the elements. 
A = (1999, 2019, 'Physics', 'Math') 
Print (A, type (A), len (A)) 
# tuple structure contains zero or one element is a particular problem, so there are some additional syntax rules 
tup1 = () # empty tuple 
tup2 = (20,) # an element necessary to add a comma after the element 
# string, list and tuple belongs sequence (sequence) 

# sets (set) 
# collection (set) is a unordered set of elements is not repeated. 
# Basic function is to be a member of testing and eliminating duplicate elements.
Student = { 'Tom', 'Jim', 'Mary', 'Tom', 'Jack', 'Rose'} 
Print (Student) # repetitive elements are automatically removed 
print ( 'Rose' in student) # membership testing ( members of the test) 
# can use braces or set () function creates a collection set, 
# NOTE: create an empty collection must be set () instead of {}, {because} is used to create an empty dictionary. 
# Set a set operation 
A = SET ( 'abcdefgabc') 
Print ( "A set as:", A) 
b = SET ( 'abcdabc') 
Print ( "b set as:", b) 
Print ( "A and b the difference between the set: ", a - b) # a and b are set difference 
print (" a and b of the union: ", a | b) # a and b and set 
print (" a and b of the intersection: " , a & b) # a and b the intersection 
print ( "a and b are not simultaneously present in the element:", a ^ b) # a and b are not simultaneously present in the element 

# dictionaries (Dictionary) 
# dictionary is a mapping types (mapping type), it is an unordered keys: The value of the collection. 
dic = {} # Create empty dictionary 
Tel = { 'Jack': 1557, 'Tom': 1320 is, 'Rose': 1886} 
Print (Tel)
print (tel [ 'Jack'] ) # main actions: by key inquiries 
del tel [ 'Rose'] # delete a key-value pair 
tel [ 'Mary'] = 4127 # to add a key-value pair 
Print (tel) 
tel [ 'Mary'] = 3434 # key to change a 
Print (Tel) 
Print (the sorted (tel.values ())) # value sorted by ascending 
print (list (tel.keys ()) ) # returns all key consisting of List 
Print ( 'Mary' not in tel) # member of the test 
print ( 'Tom' in tel)