Check a File is Opened or Closed in Python

In computer programming, working with files is something we often do. Python, a programming language, gives us useful tools to handle files. One important thing to know when dealing with files is whether a file is currently open or closed. This is crucial to avoid problems and make sure the data stays safe, especially when many things are happening at once, like different parts of a computer program trying to use the same file.

What Does it Mean to Check if a File is Opened or Closed?

In Python, when you open a file using the open() function, it establishes a connection between your program and the file on the disk. This connection allows you to perform various operations such as reading, writing, or appending data to the file. Checking if a file is opened or closed involves determining the current state of the file connection. If the file is open, attempting to open it again for writing or reading might lead to unexpected behaviors. Therefore, it is crucial to have a mechanism to verify the status of a file before attempting any operations.

Syntax:

<file_obj>.close

Returns: bool value : True – if the file is closed, False otherwise

How To Check A File Is Opened Or Closed In Python?

We can use the `closed` property on the file object. It returns `True` if the file is closed; otherwise, it returns False. Below is a Python program to check whether a file is closed.

Example 1: Check Text File is Open or Closed.

In this example, we will first open a file with the built-in open() function named `input.txt` in read mode and then use the file object’s closed property to verify whether a file is open or closed. Then, we close the file and again use the file object’s closed property to confirm that our file is closed.

Python3

# function to check whether the file is closed
def checkFileClosed(file_obj):
    # check if file is closed using `closed` property
    if file_obj.closed == True:
        print("Your file is closed.")
    else:
        print("Your file is open.")


# Opening the `input.txt` file in read mode
file_obj = open("input.txt", "r")

# check if file is closed
checkFileClosed(file_obj)

print("Now closing the file.")
# close the file
file_obj.close()

# again check if file is closed
checkFileClosed(file_obj)

Output

Using the `close` property on the file object

Example 2: Check CSV File is Open or Closed.

In this example, we will first open a file with the built-in open() function named `data.csv` in read mode and then use the file object’s closed property to verify whether a file is open or closed. Then, we close the file and again use the file object’s closed property to confirm that our file is closed.

Python3

# function to check whether the file is closed
def checkFileClosed(file_obj):
    # check if file is closed using `closed` property
    if file_obj.closed == True:
        print("Your file is closed.")
    else:
        print("Your file is open.")


# Opening the `data.csv` file in read mode
file_obj = open("data.csv", "r")

# check if file is closed
checkFileClosed(file_obj)

print("Now closing 'data.csv' file.")
# close the file
file_obj.close()

# again check if file is closed
checkFileClosed(file_obj)

Output

Conclusion

Understanding how to check whether a file is opened or closed in Python is crucial for effective file handling in large programs. The built-in open() function, with the statement and the <file_obj>.closed attribute provides a reliable way to manage file states. By implementing proper file-handling practices, you ensure the integrity of your data, which leads to the overall robustness and efficiency of your Python programs. You should ideally use the close() function to close the file after you finish performing your file operations.