Python Basic Series One: First knowledge python (ii) supplements

Basic data types

1, integral type (int)

• How to create:

  N1 = 123      # based on the Int class, an object is created n2 = Int (123) # An object is created from the Int class

• int internal optimization
  
  N1,n2 share the same block of memory,
  • The Int object in Python is the extension of the long type value in the C language
  • Small integer objects [-5, 257] are shared in Python
  • Integer objects are obtained from the buffer pool.

2. String (str)

• How to create

  S1 = "Hello" s1 = str (' Hello ')

• String (str) type and bytes type convert py3 version
  

  STR (bytes_or_buffer[, encoding[, errors]), str

  Name = "Blog Park" for I in Name:    print (i)    bytes_list = bytes (i, encoding= ' utf-8 ')    print (bytes_list)           # By default each byte is 16 binary for the X in  bytes_list:        print (X,bin (x))                # Default Every byte is a 10 binary representation

  Because of the utf-8--3 bytes
  GBK--"2 bytes
  Output Result:

  Bo B ' \xe5\x8d\x9a ' 229 0b11100101141 0b10001101154 0b10011010 guest B ' \xe5\xae\xa2 ' 229 0b11100101174 0b10101110162 0b10100010 Park B ' \xe5\x9b\xad ' 229 0b11100101155 0b10011011173 0b10101101

• Binary conversions such as:

　　　　　　

PS: General string execution of a function will generate a new content, the original content is unchanged list,tuple,dict.

3. Dictionary (dict)

• Small case, take out 123 in the dictionary:

  Li = ["Alex", 123, {"K1": "V1", "K2": {"VV": (11,22,123), "II": 456}]

  Print (li[2][' K2 ' [' VV '][2])

• The usage of Dict.fromkeys understands:

  a1= Dict.fromkeys ([' K1 ', ' K2 ', ' K3 '],[]) print (A1) a1[' K1 '].append (' 1 ') print (A1)

  　　

  
  
  

　　

Python Basic Series One: First knowledge python (ii) supplements