Summary of 2010.4.8 S21 day08 Notes

I. system

For computers, whether it is file storage/network transmission, data is essentially binary (0101010101), such as: video/picture/file stored on computers are binary; expressions/text/language/video sent by QQ/Wechat chat are all binary.

Radix:

• Binary system, internal computer.
• 8 binary system
• In general, the computer can acquire the decimal system by using the decimal system, and then automatically convert it into the binary system and operate it internally.
• Hexadecimal, commonly used to represent binary (more data with shorter content), the first edition is: x start.

II. Document Operation (Supplementary)

# Open file
f = open('File path to open',mode='r/w/a',encoding='Coding defined when a file was originally written')

# operation
data = f.read()  # Read the contents of the file into memory (all)
f.write('What to write')

# Close file
f.close()

# Example 1: Generally used for text writing.
f = open('a.txt',mode='w',encoding='utf-8')
# a. Convert "Hello" to encoding codes: 
#       "Hello" - -> 10001000100010001000100010001000100010001000100010001000100010001000100010001000100010001000100010001000100010001000100010001000100010001000100010001000100010001000
# b. Write binary into a file.
f.write('Hello') # w Opens the file, write passes in the string
f.close()

# Example 2: Generally used for picture/audio/video/unknown coding 
f = open('a.txt',mode='wb')
# f.write('Hello')  # When wb opens the file, write passes in binary, but'hello'is a string, not binary, which needs to be converted before writing. 
# 1. Convert the string to binary
data = "I am sleepy"
content = data.encode('utf-8') # Converting strings to binary by utf-8 encoding
# 2. Write the binary into the file
f.write(content) # When wb opens the file, write passes in binary
f.close()

1. File operation

• Pattern
  • R/w/a [read-only and write-only strings]***
  • R+/w+/a+ [Readable and Writable Strings]
  • Rb/wb/ab [read-only binary] ***
    • String conversion "binary":
      v = "hello"
      data = v.encode('utf-8')
    • Binary to String Conversion
      v = b'\xe6\x88\x91\xe5\xa5\xbd\xe5\x9b\xb0'
      data = v.decode('utf-8')
  • r+b / w+b / a+b [readable and writable binary]

• See (cursor byte position), regardless of whether the mode has b, is processed in bytes.

  obj = open('a.txt',mode='r',encoding='utf-8')
  obj.seek(3) # Jump to the specified byte position
  data = obj.read()
  obj.close()
  
  print(data)
  
  
  obj = open('a.txt',mode='rb')
  obj.seek(3) # Jump to the specified byte position
  data = obj.read()
  obj.close()
  
  print(data)

• tell(), which gets the current byte position of the cursor

  obj = open('a.txt',mode='rb')
  # obj.seek(3) # Jump to the specified byte position
  obj.read()
  data = obj.tell()
  print(data)
  obj.close()

• flush, forcing data in memory to be written to the hard disk

  v = open('a.txt',mode='a',encoding='utf-8')
  while True:
      val = input('Please input:')
      v.write(val)
      v.flush()
  
  v.close()

2. Close file operations

Artistic young people

v = open('a.txt',mode='a',encoding='utf-8')

v.close()

Asshole;fucker;stupid

with open('a.txt',mode='a',encoding='utf-8') as v:
    data = v.read()
    # Close the file automatically after the indented code has been executed

3. Modification of File Content

with open('a.txt',mode='r',encoding='utf-8') as f1:
    data = f1.read()
new_data = data.replace('Flying sprinkles','666')

with open('a.txt',mode='w',encoding='utf-8') as f1:
    data = f1.write(new_data)

Large Document Modification

f1 = open('a.txt',mode='r',encoding='utf-8')
f2 = open('b.txt',mode='w',encoding='utf-8')

for line in f1:
    new_line = line.replace('Asse','Death!')
    f2.write(new_line)
f1.close()
f2.close()

with open('a.txt',mode='r',encoding='utf-8') as f1, open('c.txt',mode='w',encoding='utf-8') as f2:
    for line in f1:
        new_line = line.replace('Asse', 'Death!')
        f2.write(new_line)