Advanced File Handling And Data Serialization Proficiency Exam Practice Tests

Question 1

A data logging script must record sensor readings to a file named 'log.txt' without erasing existing data. If the current file size is $S_0$ bytes and each new entry adds $k$ bytes, which mode should be used to ensure the final file size is $S_f = S_0 + n \cdot k$ after $n$ entries?

Accepted Answer

a

Answer

w

Answer

r

Answer

wb

Question 2

You are processing a binary image file where each pixel is represented by 4 bytes. To read the first $N$ pixels, you must read $B = 4N$ bytes. Which mode is required to perform this operation correctly?

Accepted Answer

rb

Answer

r

Answer

w

Answer

wb

Question 3

If a file is opened in 'w' mode, the file pointer is placed at the end of the file, and any existing data is preserved.

Accepted Answer

False

Answer

True

Question 4

Given a file containing $L$ lines, if you use the method $f.readlines()$, what is the data type of the returned object?

Accepted Answer

list

Question 5

If a script is located at '/home/user/scripts/main.py' and it attempts to open a file using the relative path '../data/input.txt', what is the absolute path of the file being accessed?

Accepted Answer

/home/user/data/input.txt

Answer

/home/user/scripts/data/input.txt

Answer

/home/data/input.txt

Answer

/home/user/scripts/../data/input.txt

Question 6

Which of the following functions from the 'os' module are used to navigate or verify the file system structure?

Answer

os.getcwd()

Answer

os.chdir()

Answer

os.path.exists()

Answer

os.open()

Question 7

If a file contains $N$ lines and you execute $f.readline()$ exactly $N+1$ times, what will the final call return?

Accepted Answer

empty string

Question 8

A file contains $N$ lines. To replace the $k$-th line where $1 \leq k \leq N$ without loading the entire file into memory, what is the most efficient algorithmic approach?

Accepted Answer

Create a temporary file, copy $k-1$ lines, write the new line, copy the remaining $N-k$ lines, and rename the temporary file to the original.

Answer

Read the entire file into a list, modify the list index $k-1$, and overwrite the original file.

Answer

Use the seek() method to jump to the start of line $k$ and overwrite the bytes directly without a temporary file.

Answer

Use the tell() method to find the end of the file and append the new content before deleting the old line.

Question 9

A file pointer is currently at position $P = 100$. After executing `f.seek(-20, 2)`, where the file size is $S = 500$ bytes, calculate the new position $P_{new}$ of the file pointer.

Accepted Answer

480

Question 10

If a binary file stores a list of $M$ objects using `pickle.dump()`, and each object has an average size of $S_{avg}$ bytes, what is the total approximate size of the binary file in bytes?

Accepted Answer

M 	imes S_{avg} + O_{overhead}

Answer

M 	imes S_{avg}

Answer

S_{avg} \div M

Answer

M^{S_{avg}}

Question 11

When using `f.seek(offset, 1)`, the `offset` value must always be a positive integer to move the pointer forward from the current position.

Accepted Answer

False

Answer

True

Question 12

Which of the following scenarios are appropriate for using the `pickle` module rather than a standard text-based CSV format?

Answer

Storing complex nested Python dictionaries that contain custom class instances.

Answer

Sharing data with a C++ application that requires a language-agnostic format.

Answer

Serializing data structures where preserving the exact Python data type (e.g., tuple vs list) is critical.

Answer

Creating a human-readable configuration file for end-users to edit.

Question 13

Given a file with 1000 bytes, if you perform `f.seek(50, 0)` followed by `f.seek(25, 1)`, what is the final value returned by `f.tell()`?

Accepted Answer

75

Question 14

In a system where you must update a binary record of size $R$ bytes at index $i$ (where $i$ is the 0-based record number), what is the correct byte offset to seek to?

Accepted Answer

Option A

Answer

Option B

Answer

Option C

Answer

Option D

Question 15

A CSV file contains $N$ rows of student data where each row is a list $[ID, Score]$. If the total sum of scores is given by $S = \sum_{i=1}^{N} Score_i$, and you are processing the file to calculate the mean score $\mu = \frac{S}{N}$, which approach minimizes memory overhead for a file where $N = 10^6$?

Accepted Answer

Iterate through the file using csv.reader() and update the sum $S$ row by row.

Answer

Load the entire file into a list of lists and then calculate the sum.

Answer

Convert the CSV to a binary file first to speed up the calculation.

Answer

Use a recursive function to read each row until the end of the file.

Question 16

In a binary file containing records of structure $R = \{ID: int, Balance: float\}$, you need to update the balance of a record with a specific $ID$. If the file size is $F$ bytes and each record is $L$ bytes, calculate the number of records $N$ in the file.

Accepted Answer

N = F / L

Question 17

When performing a deletion operation on a binary file containing $N$ records, which of the following steps are computationally necessary to maintain data integrity?

Answer

Create a temporary file to store records that do not match the deletion criteria.

Answer

Close both the original file and the temporary file after the operation.

Answer

Replace the original file with the temporary file using file renaming.

Answer

Use the seek() method to overwrite the deleted record with null bytes without shifting subsequent records.

Question 18

If a CSV file is used to store high-precision floating point numbers, the precision of the values is guaranteed to remain identical to the internal representation in memory after serialization.

Accepted Answer

False

Answer

True

Question 19

A binary file stores records of size $L = 32$ bytes. If you want to access the $k$-th record (where $k=0$ is the first record), calculate the byte offset $O$ required for the seek() operation.

Accepted Answer

O = k * 32

Question 20

Consider a binary file search algorithm where the time complexity to find a record is $T(N) = O(N)$. If we sort the records by $ID$ in the binary file, what is the theoretical minimum time complexity to find a specific record using a binary search approach?

Accepted Answer

O(log N)

Answer

O(N)

Answer

O(N^2)

Answer

O(1)

Advanced File Handling And Data Serialization Proficiency Exam Practice Tests

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Advanced File Handling and Data Serialization Proficiency Exam

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