Opening and closing files — Python: Text Input/Output Fundamentals

• How to open files
• How to close files

In this lesson, you will learn how to do the most basic operations — opening and closing of files.

How to open files

In Python, we open a file using the open function, which requires the file path and the mode as parameters. The path is straightforward. We use the mode to specify how we want to use the file:

• To write or read
• To work with text or binary data
• To clear the file before writing to it

Now, we will work with files in two modes — for reading and writing text. To read something from a file, we first need to create it and write something into it. Let's start with that. We will open a file for writing:

f = open('foo.txt', 'w')
f  # <_io.TextIOWrapper name='foo.txt' mode='w' encoding='UTF-8'>

The variable f now refers to a file object. Don't be alarmed by the type name. For now, you can pay attention only to the parameters:

• name specified when calling open
• mode specified when calling open
• encoding set to the default UTF-8, which is what you will mostly need

So, we have opened the file. Let us try to close it:

…
f.close()
f.closed  # True

Here, closed is an attribute of the f object. Attributes are variables within the associated object.

How to close files

Python is a language with automatic memory management. Knowing this, you can guess that the execution environment will close the file when we delete the last reference to the file object. It's easy.

In simple cases, we do not have to close files manually because scripts usually run briefly and don't open many files. Therefore, closing files upon script completion is generally acceptable. However, longer programs that run for extended periods may need to ensure that files are closed on time, preferably immediately after you read or write the required data to or from them.