PCEP Computer Programming and Python Fundamentals Practice Question

A team is developing a script that processes user input. They want to ensure that if the user enters a non-numeric value when asked for age, the program does not crash. Which approach should they use?

⚠ Common exam trap

The PCEP exam often tests the misconception that type checking after `input()` can prevent crashes, but candidates forget that `input()` always returns a string, making type checks like `isinstance()` useless without conversion, and that `isdigit()` is insufficient for numeric validation beyond simple positive integers.

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

✓

Use int(input()) within a try-except block

Wrapping `int(input())` in a `try-except` block catches the `ValueError` that occurs when `int()` receives a non-numeric string. This prevents the program from crashing and allows graceful handling of invalid input, which is the standard Pythonic approach for robust user input validation.

Answer analysis

Option-by-option breakdown

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

✗
Use raw_input() and then int()
Why it's wrong here
raw_input() does not exist in Python 3; it's from Python 2.
✗
Use input() with a type check after input
Why it's wrong here
This still risks crashing if conversion is attempted without exception handling.
✓
Use int(input()) within a try-except block
Why this is correct
This catches ValueError and allows graceful handling.
✗
Use a while loop to check if input.isdigit()
Why it's wrong here
This works for positive integers but fails for negative numbers or floats, and is not as flexible.

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PCEP Computer Programming and Python Fundamentals Practice Question

Why each option matters

Option-by-option breakdown

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