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Python File Modes
r
Opens a file for reading only. The file pointer is placed at the beginning of the file. This is the default mode.
rb
Opens a file for reading only in binary format. The file pointer is placed at the beginning of the file. This is the default mode.
r+
Opens a file for both reading and writing. The file pointer placed at the beginning of the file.
rb+
Opens a file for both reading and writing in binary format. The file pointer placed at the beginning of the file.
w
Opens a file for writing only. Overwrites the file if the file exists. If the file does not exist, creates a new file for writing.
wb
Opens a file for writing only in binary format. Overwrites the file if the file exists. If the file does not exist, creates a new file for writing.
w+
Opens a file for both writing and reading. Overwrites the existing file if the file exists. If the file does not exist, creates a new file for reading and writing.
wb+
Opens a file for both writing and reading in binary format. Overwrites the existing file if the file exists. If the file does not exist, creates a new file for reading and writing.
a
Opens a file for appending. The file pointer is at the end of the file if the file exists. That is, the file is in the append mode. If the file does not exist, it creates a new file for writing.
ab
Opens a file for appending in binary format. The file pointer is at the end of the file if the file exists. That is, the file is in the append mode. If the file does not exist, it creates a new file for writing.
a+
Opens a file for both appending and reading. The file pointer is at the end of the file if the file exists. The file opens in the append mode. If the file does not exist, it creates a new file for reading and writing.
ab+
Opens a file for both appending and reading in binary format. The file pointer is at the end of the file if the file exists. The file opens in the append mode. If the file does not exist, it creates a new file for reading and writing.
closeing a file
When we are done with operations to the file, we need to properly close the file.
Closing a file will free up the resources that were tied with the file and is done using Python close() method.
Python has a garbage collector to clean up unreferenced objects but, we must not rely on it to close the file.
f = open(“test.txt”)
# perform file operations
f.close()
This method is not entirely safe. If an exception occurs when we are performing some operation with the file, the code exits without closing the file.
A safer way is to use a try…finally block.
try:
f = open(“test.txt”)
# perform file operations
finally:
f.close()
This way, we are guaranteed that the file is properly closed even if an exception is raised, causing program flow to stop.
