25 Basic Python I/O Coding Questions

25 Basic Python I/O Coding Questions along with Explanations for each.

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1. Reading user input and printing it:

name = input("Enter your name: ")
print("Hello, " + name + "!")        

Explanation: This code uses the input() function to read user input and then prints a greeting with the entered name.

2. Writing to a file:

with open("output.txt", "w") as file:
  file.write("This is some text written to the file.")        

Explanation: This code opens a file named "output.txt" in write mode and writes the specified text into the file.

3. Reading from a file:

with open("input.txt", "r") as file:
  content = file.read()
  print(content)        

Explanation: This code reads the contents of a file named "input.txt" and prints the content on the console.

4. Appending to a file:

with open("output.txt", "a") as file:
  file.write("\nThis line is appended to the file.")        

Explanation: This code opens the "output.txt" file in append mode and adds a new line to the end of the file.

5. Reading line by line from a file:

with open("input.txt", "r") as file:
  for line in file:
    print(line.strip())        

Explanation: This code opens the "input.txt" file and reads its content line by line, printing each line without the newline character.

6. Using sys.stdin to read input:

import sys
data = sys.stdin.readline().strip()
print(data)        

Explanation: This code reads a line of input from the standard input using sys.stdin.readline() and then prints the input.

7. Using sys.stdout to write output:

import sys
sys.stdout.write("This is an output using sys.stdout.\n")        

Explanation: This code writes a string to the standard output using sys.stdout.write().

8. Reading and parsing CSV file:

import csv
with open("data.csv", "r") as file:
  reader = csv.reader(file)
  for row in reader:
    print(row)        

Explanation: This code reads a CSV file named "data.csv" and prints each row as a list of values.

9. Writing to a CSV file:

import csv
data = [["Name", "Age"], ["Alice", 25], ["Bob", 30]]
with open("output.csv", "w", newline="") as file:
  writer = csv.writer(file)
  writer.writerows(data)        

Explanation: This code writes a list of lists data to a CSV file named "output.csv".

10. Reading JSON from a file:

import json
with open("data.json", "r") as file:
  data = json.load(file)
  print(data)        

Explanation: This code reads a JSON file named "data.json" and loads its content into a Python data structure.

11. Writing JSON to a file:

import json
data = {"name": "Alice", "age": 25}
with open("output.json", "w") as file:
  json.dump(data, file)        

Explanation: This code writes a Python dictionary data as JSON to a file named "output.json".

12. Reading and writing binary data:

data = b"\x48\x65\x6c\x6c\x6f"
with open("binary.bin", "wb") as file:
  file.write(data)
with open("binary.bin", "rb") as file:
  content = file.read()
  print(content)        

Explanation: This code writes binary data to a file and then reads it back.

13. Using pickle for serialization:

import pickle
data = {"name": "Alice", "age": 25}
with open("data.pkl", "wb") as file:
  pickle.dump(data, file)
with open("data.pkl", "rb") as file:
  loaded_data = pickle.load(file)
  print(loaded_data)        

Explanation: This code uses the pickle module to serialize a Python dictionary and store it in a file. It then reads the pickled data back.

14. Formatting output using str.format():

name = "Alice"
age = 25
print("Name: {}, Age: {}".format(name, age))        

Explanation: This code uses the str.format() method to insert variables into the string.

15. Using f-strings for formatted output:

name = "Alice"
age = 25
print(f"Name: {name}, Age: {age}")        

Explanation: This code uses f-strings (formatted string) to insert variables directly into the string.

16. Reading from standard input until EOF (End of File):

while True
  try:
    line = input()
    print("You entered:", line)
  except EOFError:
    break:        

Explanation: This code continuously reads input from the user until it encounters the End of File (EOF) signal.

17. Redirecting standard output to a file:

import sys
original_stdout = sys.stdout
with open("output.txt", "w") as file:
  sys.stdout = file
  print("This goes to the file.")
sys.stdout = original_stdouts        

Explanation: This code temporarily redirects the standard output to a file, allowing all print statements to be written to the file.

18. Reading multiple values from a single input line:

data = input("Enter name and age (separated by space): "
name, age = data.split()
print("Name:", name)
print("Age:", age))        

Explanation: This code reads a line of input containing a name and an age (separated by a space), and then prints each value.

19. Reading integers from multiple input lines:

numbers = []
while True:
  try:
    num = int(input("Enter an integer (or 'q' to quit): "))
    numbers.append(num)
  except ValueError:
    break
print("You entered:", numbers)        

Explanation: This code repeatedly reads integers from the user until the user enters 'q' to quit, then it prints all the entered integers.

20. Reading a password without showing it on the screen:

import getpass
password = getpass.getpass("Enter your password: ")
print("Password entered.")        

Explanation: This code uses the getpass module to read a password from the user without showing it on the screen.

21. Checking if a file exists before reading from it:

import os
file_path = "data.txt"
if os.path.exists(file_path):
  with open(file_path, "r") as file:
    content = file.read()
    print(content)
else:
  print("File does not exist.")        

Explanation: This code checks if a file exists before attempting to read its content.

22. Handling file not found error:

file_path = "data.txt"
try:
  with open(file_path, "r") as file:
    content = file.read()
    print(content)
except FileNotFoundError:
  print("File not found.")        

Explanation: This code uses a try-except block to handle the case when the file is not found.

23. Writing formatted data to a file:

data = {"name": "Alice", "age": 25}
with open("output.txt", "w") as file:
  file.write(f"Name: {data['name']}, Age: {data['age']}\n")        

Explanation: This code writes formatted data to a file using f-strings.

24. Redirecting standard input from a file:

import sys
original_stdin = sys.stdin
with open("input.txt", "r") as file:
  sys.stdin = file
  data = input()
sys.stdin = original_stdin
print("Data from file:", data)        

Explanation: This code temporarily redirects the standard input to read from a file, allowing input() to read from the file.

25. Handling file writing errors:

try:
  with open("output.txt", "w") as file:
    file.write("Some data to write.")
except IOError as e:
  print("Error occurred while writing to the file:", e)        

Explanation: This code uses a try-except block to handle any errors that might occur during the file writing process.