How Python executes code - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print a greeting message.

Python

print([1])

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

A"Hello, world!"

BHello, world!

Cprint

Dgreeting

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting quotes around the text.

Trying to print a variable that is not defined.

The print function needs a string inside quotes to display text.

2fill in blank

medium

Complete the code to assign the number 5 to variable x.

Python

x = [1]

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

Ax

B"5"

Cfive

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Putting quotes around numbers.

Using variable names instead of values.

To assign a number, write the number without quotes.

3fill in blank

hard

Fix the error in the code to correctly add two numbers.

Python

result = 3 [1] 4

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

A-

B+

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using minus or other operators instead of plus.

Forgetting the operator.

The plus sign (+) adds two numbers together.

4fill in blank

hard

Fill both blanks to create a dictionary with word lengths for words longer than 3 letters.

Python

lengths = {word: [1] for word in words if len(word) [2] 3}

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

Alen(word)

B>

C<

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using word instead of len(word) for length.

Using < instead of > for filtering.

We use len(word) to get length and > 3 to filter longer words.

5fill in blank

hard

Fill all three blanks to create a dictionary with uppercase keys and values greater than zero.

Python

result = {{ [1]: [2] for k, v in data.items() if v [3] 0 }}

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

Ak.upper()

Bv

C>

Dk

Attempts:

3 left

💡 Hint

Common Mistakes

Using k instead of k.upper() for keys.

Using < or other operators instead of >.

Using k instead of v for values.

Keys are uppercased with k.upper(), values are v, and filter uses > 0.

Practice

1. What is the first step Python takes when you run a program?

easy

A. It converts the code into bytecode.

B. It immediately executes the code line by line.

C. It compiles the code into machine language.

D. It sends the code to the operating system.

Solution

1. Step 1: Understand Python's execution process

   Python first translates the source code into bytecode, which is a lower-level, platform-independent representation.

2. Step 2: Recognize what happens next

   The bytecode is then executed by the Python Virtual Machine (PVM), not the operating system directly.

3. Final Answer:

   It converts the code into bytecode. -> Option A

4. Quick Check:

   Python compiles to bytecode first [OK]

Hint: Remember: Python compiles before running [OK]

Common Mistakes:

• Thinking Python runs code directly without compiling
• Confusing bytecode with machine code
• Assuming OS runs Python code directly

2. Which of the following is the correct way to write a simple Python print statement?

easy

A. print "Hello, world!"

B. print('Hello, world!')

C. echo('Hello, world!')

D. printf('Hello, world!')

Solution

1. Step 1: Recall Python syntax for printing

   Python uses the print() function with parentheses and quotes around the string.

2. Step 2: Identify the correct syntax

   print('Hello, world!') uses print() with parentheses and quotes correctly.

3. Final Answer:

   print('Hello, world!') -> Option B

4. Quick Check:

   print() needs parentheses [OK]

Hint: Use print() with parentheses and quotes [OK]

Common Mistakes:

• Omitting parentheses in print statement
• Using echo or printf which are not Python functions
• Using print without quotes around text

3. What will be the output of this code?

print('Start')
for i in range(2):
    print(i)
print('End')

medium

A. Start\n0\n1\nEnd

B. Start\n1\n2\nEnd

C. 0\n1\nStart\nEnd

D. Start\nEnd

Solution

1. Step 1: Trace the print and loop execution

   The first print outputs 'Start'. The loop runs with i=0 and i=1, printing each. Then 'End' is printed.

2. Step 2: Write the output line by line

   Output lines are: Start, 0, 1, End.

3. Final Answer:

   Start\n0\n1\nEnd -> Option A

4. Quick Check:

   Loop prints 0 and 1 between Start and End [OK]

Hint: Remember range(2) gives 0 and 1 [OK]

Common Mistakes:

• Assuming range(2) starts at 1
• Ignoring the initial and final print statements
• Confusing loop variable values

4. Find the error in this code snippet:

for i in range(3)
    print(i)

medium

A. print() should be outside the loop

B. Indentation error on print statement

C. Missing colon ':' after range(3)

D. range() function is used incorrectly

Solution

1. Step 1: Check syntax of for loop

   Python requires a colon ':' at the end of the for statement line.

2. Step 2: Identify the missing colon

   The code misses ':' after range(3), causing a syntax error.

3. Final Answer:

   Missing colon ':' after range(3) -> Option C

4. Quick Check:

   for loops need ':' at the end [OK]

Hint: Look for missing colons in loops and conditionals [OK]

Common Mistakes:

• Forgetting the colon ':' after for statement
• Misplacing indentation but here it's correct
• Thinking range() usage is wrong

5. You want to write a program that prints numbers 1 to 5, but skips number 3. Which code correctly shows how Python executes this?

hard

A. for i in range(1,6):
if i == 3:
pass
print(i)

B. for i in range(1,5):
if i == 3:
break
print(i)

C. for i in range(1,6):
if i != 3:
break
print(i)

D. for i in range(1,6):
if i == 3:
continue
print(i)

Solution

1. Step 1: Understand the goal and loop behavior

   We want to print numbers 1 to 5 but skip printing 3. Using continue skips the current loop iteration.

2. Step 2: Analyze each option

   for i in range(1,6): if i == 3: continue print(i) uses continue to skip printing 3 and prints all others. Others either break early or print 3.

3. Final Answer:

   for i in range(1,6): if i == 3: continue print(i) -> Option D

4. Quick Check:

   continue skips printing 3 [OK]

Hint: Use continue to skip unwanted loop steps [OK]

Common Mistakes:

• Using break which stops the loop entirely
• Using pass which does nothing to skip printing
• Incorrect range limits causing missing numbers