Python  open() is  a built-in function that opens a file and returns the corresponding file object. If the file cannot be opened OSError is raised.

Python open() Syntax

f = open(file_name, access_mode)

Where,

• file_name (required) – name of the file to be opened
• access_mode (optional) – mode in which the file is to be opened. It can be read, write etc. By default, it opens the file in reading mode (r) if not specified explicitly. Here is the list of different modes in which a file can be opened.
  

  Different file modes in Python open()

  Mode	Description
  r	Opens a file for reading mode only.
  w	Opens a file for writing mode only. Creates a new file for writing it the file doesn’t exist.
  rb	Opens a binary file for reading mode only.
  wb	Opens a binary file for writing mode only. Creates a new file for writing it the file doesn’t exist.
  r+	Opens a file for reading and writing mode.
  rb+	Opens a binary file for reading and writing mode.
  w+	Opens a file for writing and reading mode. Creates a new file for writing it the file doesn’t exist.
  wb+	Opens a binary file for writing and reading mode. Creates a new file for writing it the file doesn’t exist.
  a	Opens a file for appending. Creates a new file for writing it the file doesn’t exist.
  a+	Opens a file for appending and reading. Creates a new file for reading and writing it the file doesn’t exist.
  ab	Opens a binary file for appending. Creates a new file for writing it the file doesn’t exist.
  ab+	Opens a binary file for reading and writing mode. Creates a new file for reading and writing it the file doesn’t exist.

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Recommended reading: Python Files I/O (File Handling In Python)

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Python open() Example: How to open a file in Python?

Let’s create a text file example.txt and save it in our working directory.

Now here is the code to open the file using Python open().

f = open('example.txt','r') #open file from working directory in reading mode
fp = open('C:/xyz.txt','r') #open file from any directory

In above example, f is a pointer variable pointing to the file example.txt.

To print the content of and details of example.txt, here is the code.

>>> print (*f) #print the content of file
This is a text file.
>>> print (f) #ptint mode and encoding
<_io.TextIOWrapper name='example.txt' mode='r' encoding='cp1252'>

Note that the default encoding in Windows is cp1252 whereas in Linux default encoding is utf-08.