How to open a file to write in Python?

In Python, in the domain of file handling, we come across several different types of operations; one such operation is that of opening a file for writing; this operation allows you to either create a new file or overwrite the existing content with fresh data. In this article, here, we will go through several ways on how to open a file in write mode using Python. To make it easy to understand and learn we provide for several code examples below with stepwise explanations to help master the process of writing files in Python.

Opening a File in Write Mode for Text Writing

In order to be able to open a file in write mode for writing text, follow these steps:

• Step 1: You use the open() function to open the file. You can provide the file path as the first argument and you can use the mode 'w' to indicate write mode.

• Step 2: You next assign the returned file object to a variable for upcoming operations, such as writing data to the file.

• Step 3: You then use the write() method to write text content to the file.

• Step 4: At the very end, you close the file to ensure proper handling of system resources.

Example

Suppose we have a text file as shown below

#myfile.txt
This is a test file

# Open the file in write mode for text writing
file = open('myfile.txt', 'w')
# Write text content to the file
file.write("Hello, World!")

# Lastly, you can close the file
file.close()

When we run the above code, and then open the myfile.txt, we find that its content has been overwritten and shows the following output.

Output

Hello, World!

Opening a File in Write Mode for Binary Writing

To carry out the process of opening a file in write mode for writing binary data, you follow similar steps:

• Step 1: You make use of the open() function to open the file. You can then specify the file path as the first argument and you can use the mode 'wb' to show the write mode for binary writing.

• Step 2: You then assign the returned file object to a variable for further operations, such as writing binary data to the file.

• Step 3: You also use the write() method to write binary data to the file.

• Step 4: Finally, you can close the file to ensure proper handling of system resources.

Example

Assuming we have a binary file myfile.bin, we run the following code

# Open the file in write mode for binary writing
file = open('myfile.bin', 'wb')
# Write binary data to the file
data = bytearray([0x48, 0x65, 0x6c, 0x6c, 0x6f])
file.write(data)
# Lastly, you close the file
file.close()

When the above code is run, if myfile.bin, is an empty file, it is written to as a new file or if it is an existing file, its content is overwritten.

Using Context Managers for File Writing

We must know that Python provides a convenient and elegant way to work with files using context managers. Context managers are known to automatically handle file closing, even if an exception or error occurs. Here is how you can open a file in write mode making use of a context manager:

• Step 1: You use the 'with statement' and the open() function to open the file in write mode.

• Step 2: You go on to assign the returned file object to a variable within the with block.

• Step 3: You can, lastly, write the desired content to the file within the with block.

Example

Suppose we have a text file as shown below

#myfile.txt
This is a test file

# Open the file in write mode using a context manager
with open('myfile.txt', 'w') as file:
    # Write text content to the file
    file.write("Hello, World!")

When we run the above code, and then open the myfile.txt, we find that its content has been overwritten and shows the following output.

Output

Hello, World!

Writing Multiple Lines to a File

In order to be able to write multiple lines of text to a file, you can follow these steps:

• Step 1: You use the open() function to open the file in write mode.

• Step 2: You assign the returned file object to a variable.

• Step 3: You use the write() method to write each line of text to the file. End each line with the newline character \n.

• Step 4: Last not but least, you can close the file to ensure proper handling of system resources.

Example

Suppose we have a text file as shown below

#myfile.txt
This is a test file

# Open the file in write mode
file = open('myfile.txt', 'w')

# Write multiple lines of text to the file
file.write("Line 1\n")
file.write("Line 2\n")
file.write("Line 3\n")

# Lastly, you can close the file
file.close()

When we run the above code, and then open the myfile.txt, we find that its content has been overwritten and shows the following output.

Output

    Line 1
    Line 2
    Line 3    

Appending to an Existing File

If it is required that you need to open a file and append new content to the existing content, you use the following steps:

• Step 1: You make use of the open() function to open the file in append mode. You can specify the file path as the first argument and you can use the mode 'a' to indicate append mode.

• Step 2: You then assign the returned file object to a variable for further operations, such as appending data to the file.

• Step 3: You make use of the write() method to append new content to the file.

• Step 4: At last, you can close the file to ensure proper handling of system resources.

Example

Suppose we have a text file as shown below

#myfile.txt
This is a test file

# Open the file in append mode
file = open('myfile.txt', 'a')

# Append new content to the file
file.write("This is some additional text.\n")

# Lastly, you can close the file
file.close()

When we run the above code, and then open the myfile.txt, we find that its content has been appended and shows the following output.

Output

This is a test file
This is some additional text.

The operation of opening a file for writing, in file handling, in Python, allows you to create new files or overwrite existing content with fresh data. In this current article, we have explored and discussed some examples that taught us how to open a file in write mode for text and binary writing, as well as using context managers for file writing. We also made available two additional examples that showed writing multiple lines to a file and appending to an existing file. By following the detailed explanations and code examples, you must have by now gained a sound understanding of file writing in Python. It is best to remember to close the file after writing is done so as to ensure proper handling of system resources.