Python Open Read-write file Implementation script _python

1.open

Always remember to call the close () method of the file object when you open the file with the. For example, you can use the Try/finally statement to ensure that the file is finally closed.

File_object = open (' thefile.txt ')
try:
  all_the_text = File_object.read ()
finally:
  file_ Object.close ()

Note: The Open statement cannot be placed in a try block because the close () method cannot be executed by the file object File_object when an exception is opened.

2. Read the document

Read a text file

input = open (' Data ', ' R ')
#第二个参数默认为r
input = open (' Data ')

Read binary files

input = open (' Data ', ' RB ')

Read all content

File_object = open (' thefile.txt ')
try:
  all_the_text = File_object.read ()
finally:
  file_ Object.close ()

Read fixed bytes

File_object = open (' Abinfile ', ' RB ')
try: While
  True:
    chunk = File_object.read (m)
    if not chunk:
      Break
    Do_something_with (chunk)
finally:
  file_object.close ()

Read each line

List_of_all_the_lines = File_object.readlines ()

If the file is a text file, you can also traverse the file object to get each line:

For line in File_object:
Process Line

3. Write a document

Write a text file
Output = open (' Data ', ' W ')

Write binary files
Output = open (' Data ', ' WB ')

Append Write file
Output = open (' Data ', ' w+ ')

Write Data

File_object = open (' Thefile.txt ', ' W ')
file_object.write (all_the_text)
file_object.close ()

Write Multiple lines
File_object.writelines (list_of_text_strings)

Note that calling Writelines writes to multiple lines is higher in performance than write-once writes.