Return values in Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the return statement do in a Python function?

It sends a value back to the place where the function was called, allowing the program to use that value later.

beginner

Can a Python function return more than one value?

Yes, by returning multiple values separated by commas, Python actually returns a tuple containing those values.

beginner

What happens if a Python function does not have a return statement?

The function returns None by default, which means it does not send any useful value back.

beginner

How do you capture the value returned by a function?

You assign the function call to a variable, like result = my_function(), so you can use the returned value later.

intermediate

Is it possible to have multiple return statements in one function?

Yes, you can have several return statements inside different parts of a function to return different values based on conditions.

What does a Python function return if it has no return statement?

A An empty string

B 0

C None

D An error

If no return is used, Python functions return None by default.

How can a function return multiple values in Python?

A By returning a tuple of values separated by commas

B By using multiple <code>return</code> statements at once

C By printing values instead of returning

D By calling another function inside

Returning multiple values separated by commas actually returns a tuple containing those values.

What is the correct way to get the value returned by a function?

A Use <code>input()</code> after the function

B Call the function without assignment

C Print the function name

D Assign the function call to a variable

Assigning the function call to a variable stores the returned value for later use.

Can a function have more than one return statement?

A No, only one <code>return</code> is allowed

B Yes, to return different values based on conditions

C Yes, but only if they return the same value

D No, it causes a syntax error

Multiple return statements can be used to return different values depending on conditions.

What type of value does a function return if it uses return 5, 10?

A A tuple containing (5, 10)

B A list containing [5, 10]

C An error because of multiple values

D Only the first value 5

Returning multiple values separated by commas returns a tuple with those values.

Explain in your own words what a return value is and why it is useful in a function.

Think about how a function can give you information after it finishes.

Describe how you can return multiple values from a Python function and how to use them after calling the function.

Remember that multiple values come back as a single package you can unpack.

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