Opening and closing files in Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this file reading code?

Consider the following Python code that reads a file and prints its content. What will be printed?

Python

with open('test.txt', 'w') as f:
    f.write('Hello\nWorld')

with open('test.txt', 'r') as f:
    content = f.read()
print(content)

A

Hello
World

B Hello World

C ['Hello', 'World']

D Error: file not found

💡 Hint

Remember that \n is a newline character and read() returns the whole content as a string.

The file is written with 'Hello\nWorld', so reading it returns the string with a newline. Printing it shows Hello and World on separate lines.

❓ Predict Output

intermediate

What happens if you forget to close a file?

What will be the output or effect of this code snippet?

Python

f = open('sample.txt', 'w')
f.write('Data')
print('File written')

A No output

B Error: file not closed

C File written

D Data is not saved to file

💡 Hint

Think about what print() does and what happens if you don't close a file immediately.

The print statement runs and outputs 'File written'. The file may not be flushed immediately but no error occurs.

❓ Predict Output

advanced

What is the output of this code using file context manager?

What will this code print?

Python

with open('numbers.txt', 'w') as f:
    for i in range(3):
        f.write(str(i))

with open('numbers.txt', 'r') as f:
    print(f.readline())

A 0

B Error: readline returns list

C 1

D 012

💡 Hint

readline() reads until the first newline or end of file.

The file contains '012' without newlines. readline() reads until newline or EOF, so it returns '012'. But since no newline, it returns all. So output is '012'.

❓ Predict Output

advanced

What error does this code raise?

What error will this code produce?

Python

f = open('nonexistent.txt', 'r')
content = f.read()
f.close()

A ValueError

B FileNotFoundError

C TypeError

D No error

💡 Hint

The file does not exist and is opened in read mode.

Trying to open a file that does not exist in read mode raises FileNotFoundError.

❓ Predict Output

expert

What is the value of 'lines' after this code runs?

Given this code, what is the value of the variable 'lines'?

Python

with open('data.txt', 'w') as f:
    f.write('line1\nline2\nline3')

with open('data.txt', 'r') as f:
    lines = f.readlines()

lines = [line.strip() for line in lines]

A ['line1', 'line2', 'line3']

B ['line1\n', 'line2\n', 'line3']

C ['line1 line2 line3']

D ['line1', 'line2', 'line3\n']

💡 Hint

readlines() returns lines with newline characters; strip() removes them.

readlines() returns list with newlines. The list comprehension removes newlines, so lines contains clean strings.