__name__ and __main__ behavior in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print a message only when the script is run directly.

Python

if __name__ == [1]:
    print("This script is run directly.")

Drag options to blanks, or click blank then click option'

A"__main__"

B"main"

C__main__

D"__name__"

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting the quotes around __main__

Using __main__ without quotes

Comparing to "main" instead of "__main__"

The special variable __name__ equals the string "__main__" when the script is run directly.

2fill in blank

medium

Complete the code to define a function and call it only when the script runs directly.

Python

def greet():
    print("Hello!")

if __name__ == [1]:
    greet()

Drag options to blanks, or click blank then click option'

A__main__

B"__name__"

C"__main__"

D"main"

Attempts:

3 left

💡 Hint

Common Mistakes

Calling greet() without the if condition

Using __main__ without quotes

Comparing to "main" instead of "__main__"

The function greet() should be called only if __name__ equals "__main__".

3fill in blank

hard

Fix the error in the code to print the module name when imported.

Python

print("Module name is", [1])

Drag options to blanks, or click blank then click option'

A__main__

B__name__

C"__main__"

D"__name__"

Attempts:

3 left

💡 Hint

Common Mistakes

Printing the string "__name__" instead of the variable

Using __main__ variable which is undefined

Putting quotes around __name__

The variable __name__ holds the module name or "__main__" if run directly.

4fill in blank

hard

Fill both blanks to create a script that prints differently when run or imported.

Python

def main():
    print("Running as main script")

if [1] == [2]:
    main()
else:
    print("Imported as a module")

Drag options to blanks, or click blank then click option'

A__name__

B"__main__"

C__main__

D"__name__"

Attempts:

3 left

💡 Hint

Common Mistakes

Using __main__ without quotes

Swapping the order of variable and string

Using "__name__" as string instead of variable

The condition checks if __name__ equals the string "__main__" to run main().

5fill in blank

hard

Fill all three blanks to create a script that defines a function and runs it only when executed directly.

Python

def [1]():
    print("Function called")

if [2] == [3]:
    [1]()

Drag options to blanks, or click blank then click option'

Arun_task

B__name__

C"__main__"

Dmain

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong function name

Forgetting quotes around "__main__"

Calling function outside the if block

Define function main(), check if __name__ == "__main__", then call main().

Practice

1. What does the special variable __name__ contain when a Python file is run directly?

easy

A. The file's directory path

B. The file's extension

C. "__main__"

D. The Python version

Solution

1. Step 1: Understand the role of __name__

   When a Python file runs directly, __name__ is set to the string "__main__".

2. Step 2: Differentiate direct run vs import

   If the file is imported, __name__ is the module's name, not "__main__".

3. Final Answer:

   "__main__" -> Option C

4. Quick Check:

   __name__ = "__main__" when run directly [OK]

Hint: Direct run sets __name__ to "__main__" [OK]

Common Mistakes:

• Thinking __name__ holds file path
• Confusing __name__ with Python version
• Assuming __name__ is always module name

2. Which of the following is the correct syntax to run code only when a Python file is executed directly?

easy

A. if __name__ == '__main__':

B. if __main__ == '__name__':

C. if main == '__name__':

D. if __name__ = '__main__':

Solution

1. Step 1: Check correct variable and string

   The variable is __name__ and the string to compare is "__main__".

2. Step 2: Verify syntax correctness

   Use double equals == for comparison, and colons to start the block.

3. Final Answer:

   if __name__ == '__main__': -> Option A

4. Quick Check:

   Correct syntax uses == and exact names [OK]

Hint: Use if __name__ == '__main__': exactly [OK]

Common Mistakes:

• Using single equals (=) instead of double (==)
• Swapping __name__ and __main__
• Missing colon at end of if statement

3. What will be the output when running this Python file directly?

def greet():
    print('Hello!')

if __name__ == '__main__':
    greet()

medium

A. Hello! Hello!

B. No output

C. Error: greet() undefined

D. Hello!

Solution

1. Step 1: Check if condition when run directly

   Since the file runs directly, __name__ == '__main__' is True, so greet() is called.

2. Step 2: Understand greet() function output

   The function prints "Hello!" once.

3. Final Answer:

   Hello! -> Option D

4. Quick Check:

   Function called once prints "Hello!" [OK]

Hint: Direct run triggers greet() printing once [OK]

Common Mistakes:

• Thinking greet() runs twice
• Assuming no output without main guard
• Confusing function call with definition

4. Identify the error in this code snippet:

def main():
    print('Running main')

if __name__ = '__main__':
    main()

medium

A. IndentationError in function definition

B. SyntaxError due to single equals (=) in if condition

C. NameError because main() is undefined

D. No error, code runs fine

Solution

1. Step 1: Check the if condition syntax

   The condition uses single equals (=) which is assignment, not comparison, causing SyntaxError.

2. Step 2: Confirm function and indentation

   The function main() is defined correctly and indentation is fine.

3. Final Answer:

   SyntaxError due to single equals (=) in if condition -> Option B

4. Quick Check:

   Use == for comparison, not = [OK]

Hint: Use == in if condition, not = [OK]

Common Mistakes:

• Using = instead of ==
• Assuming function undefined error
• Ignoring indentation correctness

5. You have two Python files:

# file1.py
def greet():
    print('Hi from file1')

if __name__ == '__main__':
    greet()

# file2.py
import file1
print('In file2')

What will be the output when you run file2.py?

hard

A. In file2

B. No output

C. Hi from file1

D. Hi from file1
In file2

Solution

1. Step 1: Understand import behavior with __name__

   When file1 is imported, its __name__ is "file1", not "__main__", so greet() inside the if block does NOT run.

2. Step 2: Check what runs in file2.py

   Only print('In file2') runs, so output is just "In file2".

3. Final Answer:

   In file2 -> Option A

4. Quick Check:

   Import skips main block, prints only file2 message [OK]

Hint: Imported file skips if __name__ == '__main__' block [OK]

Common Mistakes:

• Assuming greet() runs on import
• Expecting both prints always
• Confusing __name__ values on import