Explore Python’s exception handling with multiple except blocks. Learn about the execution order and potential errors in try-except statements for the PCAP-31-03 certification exam.
Table of Contents
Question
What is the expected behavior of the following code?
s = '2A' try: n = int(s) except: n = 3 except ValueError: n = 2 except ArithmeticError: n = 1
A. the code is erroneous and it will not execute
B. it outputs 1
C. it outputs 3
D. it outputs 2
Answer
The correct answer is A: the code is erroneous and it will not execute.
Explanation
This code snippet demonstrates an improper use of exception handling in Python, which is an important topic for the PCAP-31-03 certification exam. Let’s break down why this code is erroneous:
1. Multiple bare except clauses:
The first `except:` clause without a specific exception type is a bare except clause. In Python, you can only have one bare except clause, and it must be the last except block in the try-except structure. Having multiple bare except clauses is a syntax error.
2. Unreachable code:
Even if the first bare except clause was removed, the subsequent `except ValueError:` and `except ArithmeticError:` blocks would be unreachable. This is because the bare except clause catches all exceptions, leaving no possibility for the more specific exceptions to be caught.
3. Correct structure:
The proper way to structure multiple except blocks is to list the most specific exceptions first, followed by more general ones. The bare except clause, if used, should always be the last one.
4. Execution flow:
If this code were syntactically correct, it would attempt to convert the string ‘2A’ to an integer using `int(s)`. This would raise a ValueError, which would be caught by the first except block (if it were a specific exception rather than a bare except).
To fix this code and make it execute properly, you could restructure it like this:
s = '2A' try: n = int(s) except ValueError: n = 2 except ArithmeticError: n = 1 except: n = 3
In this corrected version, the ValueError would be caught first, setting n to 2.
Understanding exception handling and the proper structure of try-except blocks is crucial for the PCAP-31-03 certification exam. This question tests your knowledge of Python’s exception hierarchy and the syntax rules for exception handling.
Python Institute PCAP-31-03 certification exam practice question and answer (Q&A) dump with detail explanation and reference available free, helpful to pass the Python Institute PCAP-31-03 exam and earn Python Institute PCAP-31-03 certification.