Python 3 – File write() Method

Python is a versatile programming language that supports various operations, including file handling. A file is a collection of data that is stored on a computer’s hard drive or any other digital storage medium. Python provides various methods to handle files, and one of them is the write() method. In this article, we will discuss the write() method and how to use it to handle files.

File Handling in Python

As mentioned earlier, file handling in Python is a way of manipulating files or data stored in a computer’s hard drive or any other storage media. Python provides built-in functions and methods to make file handling easy and smooth. In Python, we can open a file using the open() method, read from it using the read() method, write to it using the write() method, and close it using the close() method.

The write() Method

The write() method is used in Python to write data to a file. It takes a single argument that represents the data to be written to the file. The syntax of the write() method is as follows:

file.write(str)

Here, file is the file object returned by the open() method, and str is the string or data that we want to write to the file. Note that the write() method does not add a new line character at the end of its output. Therefore, we need to add a new line character manually.

Let’s see an example of how to use the write() method to write data to a file:

# Open a file for writing
file = open("test.txt", "w")

# Write some content to the file
file.write("Hello, how are you?\n")
file.write("I am fine, thank you. How about you?")

# Close the file
file.close()

In this example, we first open a file named “test.txt” in write mode using the open() method. Then, we write some content to the file using the write() method. Note that we have included a new line character at the end of the first line to add a new line after the first sentence.

Working with Existing Files

The write() method can be used for both creating and modifying files. If we want to create a new file and write to it, we can use the write() method in the same way as shown in the previous example. However, if we want to modify an existing file, we need to use the “a” mode instead of the “w” mode. The “a” mode stands for “append” mode, which means that any new data that we write to the file will be added to the end of the existing data.

Let’s see an example of how to modify an existing file using the write() method:

# Open an existing file for appending
file = open("test.txt", "a")

# Write some more content to the file
file.write("\nNice to meet you.")

# Close the file
file.close()

In this example, we open the same file “test.txt” that we created earlier, but this time, we use the “a” mode instead of the “w” mode. Then, we write some more content to the file, which will be appended to the existing content. Note that we have included a new line character at the beginning of the new sentence to add a new line before the sentence.

Exception Handling

When working with files, it is essential to handle exceptions that may occur during file handling operations. The most common exceptions that may occur when working with files are the IOError and the OSError. The IOError occurs when a file operation fails, while the OSError occurs when the operating system encounters an error.

We can handle exceptions in Python using the try-except block. In the try block, we put the code that may generate an exception, and in the except block, we put the code to handle the exception. Let’s see an example of how to handle exceptions while writing to a file:

try:
    # Open a file for writing
    file = open("test.txt", "w")

    # Write some content to the file
    file.write("Hello, how are you?\n")
    file.write("I am fine, thank you. How about you?")

except IOError:
    print("Error: Failed to write to file")

finally:
    # Close the file
    file.close()

In this example, we put the code for opening the file, writing to the file, and closing the file inside the try block. This code may generate an IOError if the file operation fails. Therefore, we put the code to handle the IOError in the except block, which will print an error message if an IOError occurs. Finally, we put the code to close the file in the finally block, which will be executedregardless of whether an exception occurs or not.

Binary Files

So far, we have been working with text files, which contain human-readable text. However, Python also allows us to work with binary files, which contain non-textual data such as images, videos, and audio files. In Python, we can read and write to binary files using the same methods that we use for text files.

When working with binary files, we need to open the file in binary mode by adding a “b” to the mode string. For example, to open a file named “image.jpg” in binary mode, we can use the following code:

file = open("image.jpg", "rb")

Here, we have added a “b” to the mode string to indicate binary mode. Similarly, we can write to a binary file using the write() method, but we need to make sure that the data that we write is in binary format.

Conclusion

In this article, we discussed the write() method in Python and how to use it to write data to a file. We also saw how to work with existing files, handle exceptions, and work with binary files. The write() method is a powerful tool that can be used for a variety of applications, from simple text file manipulation to complex binary file processing.