Global keyword in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

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

Python

count = 0

def increment():
    global [1]
    count += 1

increment()
print(count)

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

Aglobal

Bcount

Cincrement

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to use the global keyword causes an error or no change to the global variable.

Using a wrong variable name after global.

The global keyword tells Python to use the global variable count inside the function, so it can be modified.

2fill in blank

medium

Complete the code to correctly update the global variable inside the function.

Python

total = 10

def add_five():
    global [1]
    total += 5

add_five()
print(total)

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

Asum

Badd_five

Cfive

Dtotal

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different variable name after global than the one declared globally.

Not using global keyword and expecting the global variable to change.

The function uses global total to modify the global variable total by adding 5.

3fill in blank

hard

Fix the error by completing the code to modify the global variable inside the function.

Python

counter = 5

def reset():
    [1] counter
    counter = 0

reset()
print(counter)

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

Aglobal

Blocal

Cnonlocal

Ddef

Attempts:

3 left

💡 Hint

Common Mistakes

Using nonlocal instead of global when the variable is global.

Not using any keyword and trying to assign to the global variable.

The global keyword is needed to tell Python that counter inside the function refers to the global variable, so it can be reset.

4fill in blank

hard

Fill in the blank to correctly modify two global variables inside the function.

Python

x = 1
y = 2

def update():
    [1] x, y
    x += 10
    y += 20

update()
print(x, y)

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

Anonlocal

Blocal

Cglobal

Ddef

Attempts:

3 left

💡 Hint

Common Mistakes

Using nonlocal instead of global.

Declaring only one variable as global and not the other.

Use global for both variables to modify them inside the function.

5fill in blank

hard

Fill in the blank to correctly use the global keyword and modify variables inside the function.

Python

a = 5
b = 10
c = 15

def change_values():
    [1] a, b, c
    a += 1
    b += 2
    c += 3

change_values()
print(a, b, c)

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

Aglobal

Ba

Cb

Dc

Attempts:

3 left

💡 Hint

Common Mistakes

Not declaring all variables as global.

Using variable names without the global keyword.

The global keyword is used to declare variables a, b, and c as global so they can be modified inside the function.

Practice

1.

What does the global keyword do in Python?

easy

A. It creates a new local variable inside a function.

B. It allows a function to modify a variable defined outside it.

C. It deletes a variable from the global scope.

D. It imports a module globally.

Solution

1. Step 1: Understand variable scopes

   Variables defined outside functions are global, inside functions are local by default.

2. Step 2: Role of global keyword

   The global keyword tells Python to use the global variable inside the function, allowing modification.

3. Final Answer:

   It allows a function to modify a variable defined outside it. -> Option B

4. Quick Check:

   global lets function change outside variable [OK]

Hint: Global lets functions change outside variables directly [OK]

Common Mistakes:

• Thinking global creates new local variables
• Confusing global with import statements
• Assuming global deletes variables

2.

Which of the following is the correct way to modify a global variable count inside a function?

count = 0
def increment():
    ?
    count += 1

easy

A. def count

B. local count

C. global count

D. nonlocal count

Solution

1. Step 1: Identify the need to modify global variable

   The function wants to increase the global variable count.

2. Step 2: Use correct keyword to access global variable

   Using global count inside the function tells Python to use the global count, not create a local one.

3. Final Answer:

   global count -> Option C

4. Quick Check:

   Use 'global' to modify global variables inside functions [OK]

Hint: Use 'global' before variable to modify it inside function [OK]

Common Mistakes:

• Using 'local' which is not a Python keyword
• Using 'nonlocal' which applies to enclosing functions, not globals
• Trying to define variable with 'def'

3.

What is the output of this code?

value = 5
def change():
    global value
    value = 10
change()
print(value)

medium

A. 5

B. Error

C. None

D. 10

Solution

1. Step 1: Analyze the function change()

   The function declares value as global and sets it to 10.

2. Step 2: Effect of calling change()

   Calling change() updates the global value from 5 to 10.

3. Final Answer:

   10 -> Option D

4. Quick Check:

   global lets function update outside variable [OK]

Hint: global changes outside variable, so print shows updated value [OK]

Common Mistakes:

• Thinking print shows original value 5
• Expecting an error without global keyword
• Confusing local and global scopes

4.

Find the error in this code and choose the fix:

counter = 0
def add():
    counter += 1
add()
print(counter)

medium

A. Add global counter inside add() before incrementing.

B. Change counter to a local variable inside add().

C. Remove the increment line counter += 1.

D. Define counter inside add() without global.

Solution

1. Step 1: Identify the error cause

   Trying to increment counter inside add() without declaring it global causes UnboundLocalError.

2. Step 2: Fix by declaring global variable

   Adding global counter inside add() tells Python to use the global counter variable.

3. Final Answer:

   Add global counter inside add() before incrementing. -> Option A

4. Quick Check:

   Declare global to modify outside variable inside function [OK]

Hint: Declare global before modifying global variable inside function [OK]

Common Mistakes:

• Ignoring the need for global declaration
• Trying to create local variable with same name
• Removing increment instead of fixing scope

5.

You want to count how many times a function is called using a global variable calls. Which code correctly updates calls each time track() runs?

calls = 0
def track():
    ?
    calls += 1

track()
track()
print(calls)

hard

A. global calls

B. nonlocal calls

C. local calls

D. calls = 0

Solution

1. Step 1: Understand the goal

   We want to update the global variable calls inside the function track().

2. Step 2: Use the correct keyword

   Using global calls inside track() allows incrementing the global calls variable.

3. Step 3: Confirm output

   Calling track() twice increments calls from 0 to 2, so print(calls) outputs 2.

4. Final Answer:

   global calls -> Option A

5. Quick Check:

   Use global to update global counter inside function [OK]

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

Common Mistakes:

• Using 'nonlocal' which is for nested functions
• Trying to assign local variable without global
• Resetting calls inside function