PCEP Practice Question: Data Types, Variables, Basic I/O and Operators
A program asks for the user's age and then prints a message: age = input("How old are you? "); print("You are " + age + " years old."). A user enters "twenty five" and the program prints "You are twenty five years old." which is not the intended numeric age. The requirement is to ensure only numeric ages are accepted and to convert the input to an integer. Which modification is the best?
⚠ Common exam trap
Candidates often choose Option B (isdigit) thinking it is sufficient, but they overlook that `isdigit()` does not handle spaces or negative numbers and does not loop to re-prompt, while the correct solution must combine error handling with a loop to meet the requirement of repeatedly asking until valid input is provided.
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 a try-except in a loop to repeatedly ask until valid integer is entered: while True: try: age = int(input("How old are you? ")) break except ValueError: print("Invalid.")
It uses a `while True` loop with a `try-except` block to repeatedly prompt the user until a valid integer is entered. The `int()` conversion raises a `ValueError` for non-numeric strings like "twenty five", and the `except` clause catches that error and prints "Invalid." without breaking the loop, ensuring only numeric ages are accepted and converted to an integer.
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 try-except to catch ValueError and print an error message, then exit.
Why it's wrong here
Does not allow re-entry; program ends.
- ✗
Check if age.isdigit() before converting, and if not, ask again.
Why it's wrong here
Rejects valid negative numbers and floats; not fully robust.
- ✗
Assume the user will always enter a number; no changes needed.
Why it's wrong here
Does not handle invalid input as required.
- ✓
Use a try-except in a loop to repeatedly ask until valid integer is entered: while True: try: age = int(input("How old are you? ")) break except ValueError: print("Invalid.")
Why this is correct
Correct; robustly handles all non-integer inputs.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCEP practice question is part of Courseiva's free Python Institute certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCEP exam.