Return values in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to return the sum of two numbers.

Python

def add(a, b):
    return a [1] b

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

A-

B+

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction or multiplication instead of addition.

The return statement sends back the result of a + b.

2fill in blank

medium

Complete the code to return the first character of a string.

Python

def first_char(s):
    return s[1]

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

A[1]

B[-1]

C[:1]

D[0]

Attempts:

3 left

💡 Hint

Common Mistakes

Using index 1 which is the second character.

Using negative index which gives last character.

Index 0 gives the first character of a string in Python.

3fill in blank

hard

Fix the error in the function to return the square of a number.

Python

def square(n):
    result = n [1] n
    return result

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

A*

B+

C-

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition or subtraction instead of multiplication.

Multiplying n by itself gives the square.

4fill in blank

hard

Fill both blanks to return a dictionary with words as keys and their lengths as values for words longer than 3 letters.

Python

def word_lengths(words):
    return {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 the word itself as value instead of its length.

Using wrong comparison operator.

The dictionary comprehension uses len(word) as value and filters words with length greater than 3 using >.

5fill in blank

hard

Fill all three blanks to return a dictionary with uppercase keys and values only if the value is positive.

Python

def filter_positive(data):
    return { [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 original keys instead of uppercase.

Using wrong comparison operator or filtering condition.

The dictionary comprehension uses uppercase keys with k.upper(), values v, and filters values greater than zero with >.

Practice

1. What does the return statement do in a Python function?

easy

A. It sends a value back to where the function was called.

B. It prints a value to the screen.

C. It creates a new variable inside the function.

D. It pauses the function without sending any value.

Solution

1. Step 1: Understand the purpose of return

   The return statement ends the function and sends a value back to the caller.

2. Step 2: Differentiate from printing or pausing

   Printing shows output but does not send a value back; pausing does not return a value.

3. Final Answer:

   It sends a value back to where the function was called. -> Option A

4. Quick Check:

   Return sends value back [OK]

Hint: Return sends value back, print shows output only [OK]

Common Mistakes:

• Confusing return with print
• Thinking return pauses without value
• Assuming return creates variables

2. Which of the following is the correct syntax to return the value 10 from a function?

easy

A. return(10,)

B. return 10

C. return = 10

D. return: 10

Solution

1. Step 1: Recall correct return syntax

   The correct syntax is simply return followed by the value without assignment or colon.

2. Step 2: Check each option

   return 10 is correct; return(10,) returns a tuple (10,) due to the trailing comma; the others cause syntax errors.

3. Final Answer:

   return 10 -> Option B

4. Quick Check:

   Return value with 'return value' syntax [OK]

Hint: Use 'return value' without assignment or colon [OK]

Common Mistakes:

• Using assignment with return
• Adding colon after return
• Using parentheses incorrectly

3. What is the output of this code?

def add(a, b):
    return a + b

result = add(3, 4)
print(result)

medium

A. None

B. 34

C. 7

D. Error

Solution

1. Step 1: Understand the function behavior

   The function add returns the sum of a and b.

2. Step 2: Calculate the return value

   Calling add(3, 4) returns 7, which is stored in result and printed.

3. Final Answer:

   7 -> Option C

4. Quick Check:

   3 + 4 = 7 [OK]

Hint: Return value is sum, printed as 7 [OK]

Common Mistakes:

• Concatenating numbers as strings
• Forgetting to return value
• Expecting print inside function

4. Find the error in this function and choose the correct fix:

def multiply(x, y):
    product = x * y
    print(product)

medium

A. Add return x, y instead of product.

B. Change print(product) to return print(product).

C. Remove product and just print x * y.

D. Add return product to send the result back.

Solution

1. Step 1: Identify the problem

   The function prints the product but does not return it, so no value is sent back.

2. Step 2: Fix by returning the product

   Adding return product sends the result back to the caller.

3. Final Answer:

   Add return product to send the result back. -> Option D

4. Quick Check:

   Return value to send result back [OK]

Hint: Return value to send it back, print only shows output [OK]

Common Mistakes:

• Returning print() instead of value
• Not returning any value
• Returning wrong variables

5. You want a function that returns the first non-empty string from a list or None if all are empty. Which function correctly does this?

hard

A. def first_non_empty(strings):
for s in strings:
if s:
return s
return None

B. def first_non_empty(strings):
for s in strings:
if s == '':
return s
return None

C. def first_non_empty(strings):
for s in strings:
if not s:
return s
return None

D. def first_non_empty(strings):
for s in strings:
return s
return None

Solution

1. Step 1: Understand the goal

   The function should return the first string that is not empty (truthy) or None if none found.

2. Step 2: Analyze each option

   The version with if not s: return s returns the first falsy (empty) string; if s == '' returns the first exactly empty string; if s: return s returns the first truthy (non-empty) string; the version without if returns the first string regardless. Only the truthy check is correct.

3. Final Answer:

   def first_non_empty(strings): for s in strings: if s: return s return None -> Option A

4. Quick Check:

   Return first truthy string or None [OK]

Hint: Return first truthy value, else None [OK]

Common Mistakes:

• Returning empty strings instead of non-empty
• Returning on first loop without condition
• Confusing truthy and falsy values