20 File Handling Interview Questions and Answers

File Handling is an important topic for any programming language. When you are interviewing for a position that involves programming, you can expect to be asked questions about how you would handle files. An interviewer wants to know that you understand the basics of file handling and that you are familiar with the different functions that are available. In this article, we will review some of the most common File Handling interview questions and how you should answer them.

File Handling Interview Questions and Answers

Here are 20 commonly asked File Handling interview questions and answers to prepare you for your interview:

1. Can you explain how file handling is done in Python?

File handling in Python is done using what is called a file object. A file object is created using the open() function, and then various methods can be called on that file object to read from or write to the file. For example, the read() method can be called on a file object to read the contents of a file, and the write() method can be called to write data to a file.

2. What are the different modes for opening a file in Python?

The different modes for opening a file in Python are “r” for read-only, “w” for write-only, “a” for append-only, and “r+” for read/write.

3. How do you create and open a text file using Python?

You can create and open a text file using the Python built-in open() function. This function takes two arguments: the name of the file to be created or opened, and the mode in which the file should be opened. The mode argument is optional and defaults to ‘r’ for reading mode. To open a file in write mode, you would use ‘w’ as the mode argument.

4. How do you read data from a given text file using Python?

You can use the built-in open() function to open a text file and read its contents. For example:

with open(‘filename.txt’) as f:
data = f.read()

This will read the entire contents of the file into the variable data.

5. Why does an error occur when trying to write to a read-only file?

When you try to write to a read-only file, an error occurs because you are not allowed to modify the file. The file is marked as read-only, which means that it can only be opened for reading and not for writing.

6. Is it possible to append data to an existing file? If yes, then can you tell me how?

Yes, it is possible to append data to an existing file. This can be done by opening the file in append mode, using the “a” flag when opening the file. This will allow you to write to the end of the file, rather than overwriting the existing data.

7. What is the best way to check whether a file exists or not?

The best way to check whether a file exists or not is to use the try-except statement. This statement will allow you to attempt to open the file, and if it does not exist, an exception will be raised.

8. How do you rename a file in python?

You can use the os.rename() function to rename a file in python.

9. How do you delete a file in python?

You can delete a file in python using the os module. The os module has a function called os.remove() which will delete the file you specify.

10. What is the use of with statement in Python?

The with statement is used to wrap the execution of a block of code within an object. This is most commonly used with files, where the with statement will automatically close the file once the block of code has been executed. This ensures that the file is properly closed and can help to avoid potential errors.

11. Can you explain what pickling and unpickling mean in context of Python?

Pickling is the process of converting a Python object into a byte stream, so that it can be stored in a file or transmitted over a network. Unpickling is the process of converting a byte stream back into a Python object.

12. What’s the difference between a binary file and a text file?

A binary file is any file that is not a text file. A binary file can store any type of data, and is not limited to storing only text data. A text file, on the other hand, is a file that contains only text data.

13. How can you modify permissions on a file in Python?

You can use the chmod() function in the os module to modify permissions on a file.

14. What is the advantage of using the CSV module over other methods of parsing files in Python?

CSV is a very common file format, and the CSV module in Python makes it easy to read and write files in this format. The module handles all of the details of parsing and formatting the data, so you can focus on working with the data itself. Additionally, the CSV module can be used with a wide variety of other software, making it a good choice for data exchange.

15. How would you go about reading a comma-separated value (CSV) file into memory?

One approach would be to use the fgetcsv function, which is built into PHP. This function takes a file handle as its first argument and then an optional integer length value. It returns an array of fields read from the CSV file.

16. How can you replace all occurrences of a specific word in a text file without having to parse through each line individually?

You can use the replaceAll() method from the String class.

17. How do you sort a dictionary by its keys in Python?

You can use the sorted() function to sort a dictionary by its keys in Python. The sorted() function takes a dictionary as an argument and returns a list of tuples, where each tuple consists of a key and a value. You can then use this list of tuples to create a new dictionary.

18. What do you understand about the default encoding system in Python?

The default encoding system in Python is ASCII. This means that any characters outside of the ASCII range will be encoded using a replacement character.

19. What is the easiest way to sort a list in descending order?

The easiest way to sort a list in descending order is to use the reverse() method. This will take a list and reverse the order of the elements in the list.

20. What exactly does the “with” keyword do in Python?

The with keyword is used to create a context manager. This allows you to specify a block of code that will be executed as a unit. The with keyword will automatically take care of opening and closing files for you, which can be helpful in ensuring that your files are properly handled.