How to use the open() function to open a file in Python 2.x

How to use the open() function to open a file in Python 2.x

In the Python 2.x version, you can use the open() function to open and operate files. The open() function accepts two parameters: file name and open mode. The filename can be a relative or absolute path, and the opening mode determines how the file is manipulated. The following will introduce the usage of the open() function and provide some sample code.

Open mode:

• 'r': read-only mode. The file must exist, otherwise a FileNotFoundError exception will be thrown, default mode.
• 'w': writing mode. If the file already exists, clear the original content and write from scratch; if the file does not exist, create a new file.
• 'a': Append mode. If the file already exists, append the content to the end of the file; if the file does not exist, create a new file.
• 'b': Binary mode. Used in conjunction with other modes for binary operations.
• ' ': Open a file for update (read and write).

The sample code is as follows:

1. Open the file in read-only mode and read the content:

file = open('example.txt', 'r')
content = file.read()
print(content)
file.close()

2. In write mode Open the file, write the content and save:

file = open('example.txt', 'w')
file.write('Hello, world!')
file.close()

3. Open the file in append mode, append the content at the end of the file:

file = open('example.txt', 'a')
file.write('
This is a new line.')
file.close()

4. With only Open the file in read mode and read the contents line by line:

file = open('example.txt', 'r')
for line in file:
    print(line)
file.close()

5. Use the with statement to open the file and automatically close the file at the end of the code block:

with open('example.txt', 'r') as file:
    content = file.read()
    print(content)

It should be noted that after using the open() function to open a file, it is best to close the file after the operation is completed to release resources and avoid potential errors. You can use the close() method to close the file, or use the with statement, which will automatically close the file.

In addition, when processing files, you can also use other related methods to operate files, such as readline(), readlines(), write(), etc. Choose the appropriate method according to specific needs.

Summary: The above is how to use the open() function in Python 2.x, including the mode of opening files and some common operations. Through these sample codes, you can better understand how to use the open() function in Python to open and operate files. Remember to close files after working on them to develop good habits.

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