Basic operation of file

Two, basic file operations

< strong>In Python you need to remember 1 function and 3 methods to manipulate files

open The function is responsible for opening File and return the file object
read/write/close All three methods need to be called through the file object< /p>

Example of reading file

# 1\. Open-File name needs to be capitalized

file = open("README")



# 2\. Read

text = file.read()

print(text)



# 3\. Close

file.close()

3. Ways to open files

Example of writing file

# Open file

f = open("README", "w")



f.write("hello python!\n ")

f.write("It’s really nice today< span style="color: #800000;">")



# Close file

f.close()

# Open file

file = open("README")



while True:

 # read a line of content

 text = file.readline()



 # Determine whether to read the content

 if not text:

 break



 # There is already a `\n` at the end of each line read

 print(text, end="")



# Close file

file.close()

Four. File management operations

V. Encoding format of text files

• The content stored in text files is a file based on character encoding, which is common The encoding includes ASCII encoding, UNICODE encoding, etc.
• Python 2.x uses ASCII encoding format by default, Python 3.x uses UTF-8 encoding format by default

• ASCII Encoding

  • Only 256 ASCII characters in the computer
  • One ASCII< /code> Occupies 1 byte space in the memory
    • 8 0/1 permutation and combination methods total There are 256 types, that is, 2 ** 8

  UTF -8 encoding format

  • The computer uses 1~6 bytes to represent a UTF-8 Characters, covering texts in almost all regions on the earth
  • Most Chinese characters use 3 bytes to represent
  • UTF-8 is an encoding format of UNICODE encoding

  How to use Chinese in Ptyhon 2.x?

  • Add code in the first line of the Python 2.x file# *-* coding:utf8 *-* , The interpreter will process python files with utf-8 encoding, this method is officially recommended!
  • You can also use # coding=utf8.

  How to traverse unicode strings correctly in Python 2.x?

  • In Python 2.x, even if the file is specified to use the UTF-8 encoding format, it will still < strong>Traverse the string in bytes
  • To be able to traverse the string correctly, When defining the string, Enclose the string in quotation marks Before, add a lowercase letter u to tell the interpreter that this is a unicode string (using UTF-8 encoding format) String)

  # *-* coding:utf8 *-*
  
  
  
  # Before the string, add a `u` to indicate that the string is a utf8 String
  
  hello_str = u"Hello world"
  
  
  
  print(hello_str)
  
  
  
  for c in hello_str:
  
   print(c)

# 1 \. Open-File name needs to be capitalized

file = open("README")



# 2\. Read

text = file.read()

print(text)



# 3\. Close

file.close()

# Open file

f = open("README", "w")



f.write("hello python!\n ")

f.write("It’s really nice today< span style="color: #800000;">")



# Close file

f.close()

# Open file

file = open("README")



while True:

 # read a line of content

 text = file.readline()



 # Determine whether to read the content

 if not text:

 break



 # There is already a `\n` at the end of each line read

 print(text, end="")



# Close file

file.close()

# *-* coding:utf8 *-*



# Before the string, add a `u` to indicate that the string is a utf8 String

hello_str = u"Hello world"



print(hello_str)



for c in hello_str:

 print(c)