PCEP Practice Question: Functions, Tuples, Dictionaries and Exceptions

A developer writes a function that should return the sum of two numbers, but the code returns 0 instead. What is the most likely cause?

def add(a, b):

result = a + b

print(add(3, 4))

⚠ Common exam trap

Python Institute often tests the distinction between computing a value inside a function and actually returning it — the trap here is that candidates see `result = a + b` and assume the sum is automatically output, missing the critical absence of the `return` statement.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

The function does not have a return statement.

The function `add` computes `a + b` and assigns it to `result`, but lacks a `return` statement. In Python, a function without an explicit `return` automatically returns `None`. When `print(add(3, 4))` is executed, it prints `None`, not the sum. The question states the code returns 0, which is a common misreading — the actual output is `None`, but the core issue is the missing `return`.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
The function is not defined before the call.
Why it's wrong here
The function is defined before the print statement.
✗
The variable 'result' is not defined.
Why it's wrong here
The variable is defined and assigned inside the function.
✗
The function parameters are of incompatible types.
Why it's wrong here
Both parameters are integers, no type conflict.
✓
The function does not have a return statement.
Why this is correct
The function computes the sum but does not return it, returning None instead.

Go deeper

PCEP Practice Question: Functions, Tuples, Dictionaries and Exceptions

Why each option matters

Option-by-option breakdown

Related to this question