day3 ----- python basic data types

  Basic data types

Data: Status Description of the measure data

Type: different things require different types of storage

• Int int

  Definition: age, phone number, etc. is an integer number

  B string into integer 
  b = '12 is' 
  Print ( type ( b)) 
  b = int ( b) 
  Print ( type ( b)) < class 'STR' > < class 'int' >
  
  
  

   

• Float float

  Definition: weight, height and so there is a decimal point

  = F1 1.9   # F1 = a float (1.9) 
  Print ( type ( F1)) < class 'a float' > string into float F2 = '1.9' F2 = a float ( F2) Print ( type ( F2)) < class 'a float' >
  
  
  
  
  
  
  
  
  
  
  

• String str

  Definition: keep some descriptive information, keep personal interests, personal profiles

  String quotes are no different, but can not be mixed.

  If the string needs quotation marks, it must be nested. # S2 = 'asas "sd"'

  s1 = 'sean'   #s1 = str(sean)
  ​
  print(type(s1))
  print(id(s1))
  print(s1)
  ​
  <class 'str'>
  2945322521392
  sean

  python2: 
      STR nature actually have a bit with 8-bit serial     to python3:     STR sequence unicode nature actually        1024G 1T =    1024M. 1G =    1024KB = 1M    1024B = 1KB    . IB = 8bit
  
  
  
   
         
  
  
  
  
  

  String concatenation is to open up a new memory space, the value after you deposit into stitching.

  s3 = 'hello'
  ​
  s4 = 'world'
  ​
  print(s3 +s4)
  ​
  helloworld

• List list

  Definition: a stored value or a plurality of different types of

  In the count is zero programming

  Y = [ 'elephant', 'beautiful', [ 'Read', 'Study']] 
  Print ( Y) 
  Print ( type ( Y)) Print ( Y [ 0]) print result: [ 'elephant' , 'beautiful', [ 'Read', 'Study']] < class 'List' > elephant
  
  
  
  
  
  
  

  In the list there is a list of values. = L1 [    [ 'Egon', 73 is, 'hot head', [ 'singing', 'jumping', 'RAP']],    [ 'Alex', 84, 'beauty'] ] Print ( L1 [ 0] [ . 1]) Print ( L1 [ . 1] [ 2]) Print ( L1 [ 0] [ . 3] [ 2]) print result: 73 beautiful rap
  
  
  
  
  
  
  
  
  
  
  
  
  

• Dictionary type dict

  The method defined: {} stored data by key: value defines the mapping relationship between key-value pairs,

  Each value is separated by commas.

  d1 = {"name": 'sean', 'age': 18}  # d1 = dict({"name":'sean','age':18})
  ​
  print(d1['name'])
  print(type(d1))
  ​
  d2 = {'name':'tank','age':73,'hobby':[ 'piao', '妹子']}
  ​
  print(d2['hobby'][0])
  ​
  打印结果：
  sean
  <class 'dict'>
  piao

• Boolean

  Definition: mainly used to judge right and wrong things

  General does not define a separate boolean

  tag = True  # tag = bool(True)
  tag1 = False  # tag = bool(False)

  = A . 1 
  B = . 1 
  Print ( A == B)   # equal sign is the comparison value (value) 
  Print ( A IS B)   # IS comparison is id (address) print result: True True