Python File Operation

A file is a named location used for storing data. For example, main.py is a file that is always used to store Python code.

Python provides various functions to perform different file operations, a process known as File Handling.

Opening Files in Python

In Python, we need to open a file first to perform any operations on it—we use the open() function to do so. Let's look at an example:

Suppose we have a file named file1.txt.

To open this file, we can use the open() function.

file1 = open("file1.txt")

Here, we have created a file object named file1. Now, we can use this object to work with files.

file1 = open("file1.txt")

# open a file in default mode (read and text)
file1 = open("test.txt")      # equivalent to open("test.txt", "rt")

# open a file in write and text mode 
file1 = open("test.txt",'w')  

# open a file in read, write and binary mode
file1 = open("img.bmp",'+b') 

file_path = "/home/user/documents/file1.txt"
file1 = open(file_path)

Reading Files in Python

After we open a file, we use the read() method to read its content. For example,

Suppose we have a file named file1.txt.

Now, let's read the content of the file.

# open a file in read mode
file1 = open("file1.txt")

# read the file content
read_content = file1.read()
print(read_content)

Output

This is a test file.
Hello from the test file.

In the above example, the code file1.read() reads the content of the file and stores it in the read_content variable.

Note: If you need clarification about how the code file1.read() works, please visit Working of Python Objects.

Writing to Files in Python

To write to a Python file, we need to open it in write mode using the w parameter.

Suppose we have a file named file2.txt. Let's write to this file.

# open the file2.txt in write mode
file2 = open('file2.txt', 'w')

# write contents to the file2.txt file
file2.write('Programming is Fun.\n')
file2.write('Programiz for beginners\n')

When we run the above code, we will see the specified content inside the file.

Be Careful While Writing to a File

If we try to perform the write operation to a file that already has some content, the new content will replace the existing ones. For example,

Suppose we have a file named file2.txt.

Now let's write to this file.

# open the file2.txt in write mode
file2 = open('file2.txt', 'w')

# write new contents to the file2.txt file
file2.write('Learning Python is interesting.\n')
file2.write('File operations are useful.\n')

When we run the above code, the new content will replace any existing content in file2.txt.

Note: If we try to open a file that doesn't exist, a new file is created, and the write() method will add the content to the file.

Closing Files in Python

When we are done performing operations on the file, we need to close the file properly. We use the close() function to close a file in Python. For example,

# open a file
file1 = open("file1.txt", "r")

# read the file
read_content = file1.read()
print(read_content)

# close the file
file1.close()

Output

This is a test file.
Hello from the test file.

Note: Closing a file will free up the resources that are tied to the file. Hence, it is a good programming practice to always close the file.

Opening a Python File Using with...open

In Python, there is a better way to open a file using with...open. For example,

with open("file1.txt", "r") as file1:
    read_content = file1.read()
    print(read_content)

Output

This is a test file.
Hello from the test file.

Here, with...open automatically closes the file, so we don't have to use the close() function.

Note: Since we don't have to worry about closing the file, make a habit of using the with...open syntax.

try:
    file1 = open("file1.txt", "r")
    read_content = file1.read()
    print(read_content)

finally:
    # close the file
    file1.close()

This is a test file.
Hello from the test file.