Global scope in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print the global variable count inside the function.

Python

count = 10

def show_count():
    print([1])

show_count()

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

Aglobal

Blocal_count

C10

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to use a variable name that is not defined.

Using the keyword 'global' instead of the variable name.

The variable count is defined outside the function, so it is a global variable. To access it inside the function, just use its name count.

2fill in blank

medium

Complete the code to modify the global variable score inside the function.

Python

score = 5

def increase_score():
    global [1]
    score += 1

increase_score()
print(score)

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

Avalue

Bscore

Cpoints

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to declare the variable as global before modifying it.

Using a different variable name in the global statement.

To change a global variable inside a function, you must declare it as global followed by its name. Here, the global variable is score.

3fill in blank

hard

Fix the error by completing the code to correctly print the global variable name inside the function.

Python

name = "Alice"

def greet():
    print([1])

greet()

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

Aname

BName

C"name"

Dglobal name

Attempts:

3 left

💡 Hint

Common Mistakes

Using a capitalized variable name Name which is undefined.

Trying to print the string "name" instead of the variable.

The variable name is global and should be used exactly as defined. Variable names are case-sensitive, so Name is different and undefined.

4fill in blank

hard

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

Python

words = ["apple", "cat", "banana", "dog"]
lengths = {word: [1] for word in words if len(word) [2] 3}
print(lengths)

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

Alen(word)

B>

C<

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using the word itself instead of its length.

Using less than symbol which filters shorter words.

The dictionary comprehension uses len(word) to get the length of each word. The condition len(word) > 3 filters words longer than 3 letters.

5fill in blank

hard

Fill all three blanks to create a dictionary with uppercase keys and values only for positive values.

Python

data = {"a": 1, "b": -2, "c": 3}
result = { [1]: [2] for k, v in data.items() if v [3] 0 }
print(result)

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

Ak.upper()

Bv

C>

Dk

Attempts:

3 left

💡 Hint

Common Mistakes

Using the original key without uppercase.

Filtering values less than or equal to zero.

The dictionary comprehension uses k.upper() to make keys uppercase, keeps values v, and filters only positive values with v > 0.

Practice

1. What does the global keyword do inside a Python function?

easy

A. It deletes a global variable.

B. It creates a new local variable inside the function.

C. It makes the function run faster.

D. It allows the function to modify a variable defined outside the function.

Solution

1. Step 1: Understand the role of global keyword

   The global keyword tells Python that the variable inside the function refers to the variable defined outside (in global scope).

2. Step 2: Effect on variable modification

   Without global, assigning a value creates a new local variable. With global, it modifies the existing global variable.

3. Final Answer:

   It allows the function to modify a variable defined outside the function. -> Option D

4. Quick Check:

   global keyword modifies outer variable [OK]

Hint: global lets functions change outside variables [OK]

Common Mistakes:

• Thinking global creates a new local variable
• Assuming global deletes variables
• Believing global affects performance

2. Which of the following is the correct way to declare a global variable inside a function?

easy

A. def global x:

B. global = x

C. global x

D. x global

Solution

1. Step 1: Recall correct syntax for global declaration

   The correct syntax is to write the keyword global followed by the variable name, separated by a space.

2. Step 2: Check each option

   global x matches the correct syntax. Others are invalid Python syntax.

3. Final Answer:

   global x -> Option C

4. Quick Check:

   global keyword followed by variable name [OK]

Hint: Use 'global' then variable name to declare global inside function [OK]

Common Mistakes:

• Using '=' with global keyword
• Trying to define global like a function
• Placing global after variable name

3. What will be the output of this code?

count = 5
def increment():
    global count
    count += 1
increment()
print(count)

medium

A. 6

B. None

C. Error

D. 5

Solution

1. Step 1: Understand the global variable usage

   The variable count is defined globally with value 5. Inside increment(), global count allows modifying this global variable.

2. Step 2: Trace the function call and print

   The function adds 1 to count, changing it from 5 to 6. Then print(count) outputs 6.

3. Final Answer:

   6 -> Option A

4. Quick Check:

   global lets function change count to 6 [OK]

Hint: global lets function update outside variable [OK]

Common Mistakes:

• Expecting original value 5 to print
• Thinking global causes error here
• Assuming function returns None

4. Find the error in this code:

total = 10
def add():
    total += 5
add()
print(total)

medium

A. Missing global declaration inside add()

B. Syntax error in function definition

C. total is not defined globally

D. print statement is incorrect

Solution

1. Step 1: Identify variable scope issue

   Inside add(), total += 5 tries to modify total. Without global total, Python treats total as local but it's used before assignment, causing an error.

2. Step 2: Fix by adding global declaration

   Adding global total inside add() tells Python to use the global total variable, fixing the error.

3. Final Answer:

   Missing global declaration inside add() -> Option A

4. Quick Check:

   Modify global variable needs global keyword [OK]

Hint: Add global keyword to modify global variable inside function [OK]

Common Mistakes:

• Ignoring need for global keyword
• Thinking total is local automatically
• Assuming no error occurs

5. You want to count how many times a function is called using a global variable. Which code correctly updates the global counter?

hard

A. calls = 0
def func():
calls += 1
func()
print(calls)

B. calls = 0
def func():
global calls
calls += 1
func()
print(calls)

C. calls = 0
def func():
calls = calls + 1
func()
print(calls)

D. calls = 0
def func():
global calls
calls = calls
func()
print(calls)

Solution

1. Step 1: Understand global variable modification

   To update a global variable inside a function, you must declare it with global inside the function.

2. Step 2: Analyze each option

   calls = 0 def func(): calls += 1 func() print(calls) tries to increment without global, causing error. calls = 0 def func(): global calls calls += 1 func() print(calls) correctly uses global calls and increments. calls = 0 def func(): calls = calls + 1 func() print(calls) tries to read and assign without global, causing UnboundLocalError. calls = 0 def func(): global calls calls = calls func() print(calls) declares global but does not increment.

3. Final Answer:

   calls = 0 def func(): global calls calls += 1 func() print(calls) -> Option B

4. Quick Check:

   global keyword needed to update global variable [OK]

Hint: Use global keyword to update global counter inside function [OK]

Common Mistakes:

• Forgetting global keyword causes UnboundLocalError
• Assigning without global causes UnboundLocalError when reading variable
• Declaring global but not updating variable