To handle file reading errors, I would use a try-except-finally block (or equivalent in the chosen language). The try block would contain the code that attempts to open and read the file. The except block would be used to catch specific exceptions that might occur during the file operation. The finally block would ensure that the file is closed, regardless of whether an exception occurred or not. Using specific exception types is crucial for several reasons:

• Precise Error Handling: Specific exception types allow for targeted error handling. For example, if the file doesn't exist, I can provide a user-friendly message indicating that the file is missing. If the file is corrupted, I can attempt to log the error and potentially offer a recovery mechanism.
• Avoids Catching Unexpected Errors: Catching a generic Exception can mask unexpected errors that were not anticipated. This can make debugging difficult.
• Improved Code Clarity: Using specific exception types makes the code more readable and easier to understand. It clearly indicates the types of errors that the code is designed to handle.

Python Example:

try:
with open("data.txt", "r") as f:
data = f.read()
print("File read successfully:", data)
except FileNotFoundError:
print("Error: File 'data.txt' not found.")
except IOError as e:
print("Error reading file:", e)
except Exception as e:
print("An unexpected error occurred:", e)
finally:
if 'f' in locals() and f: #check if f is defined and not None
f.close()
print("File closed.")

This example demonstrates how to handle FileNotFoundError, IOError, and a generic Exception. The finally block ensures that the file is closed, even if an error occurs.

Model Answer 1

This solution demonstrates how to read a file, process the content (counting words), and write the results to another file. It includes error handling for file existence.

import re

def processfile(inputfilename, output_filename):

try:

with open(input_filename, 'r', encoding='utf-8') as infile:

text = infile.read()

except FileNotFoundError:

print(f"Error: File '{input_filename}' not found.")

return

words = re.findall(r'\b\w+\b', text.lower()) # Extract words, convert to lowercase

word_counts = {}

for word in words:

wordcounts[word] = wordcounts.get(word, 0) + 1

try:

with open(output_filename, 'w', encoding='utf-8') as outfile:

for word, count in word_counts.items():

outfile.write(f"{word}: {count}\n")

except Exception as e:

print(f"Error writing to file '{output_filename}': {e}")

if name == "main":

input_file = "data.txt"

outputfile = "wordcounts.txt"

processfile(inputfile, output_file)

Explanation:

• The code first attempts to open the input file. If the file is not found, it prints an error message and exits.
• It reads the entire content of the file into a string.
• The re.findall() function is used with a regular expression to extract all words from the text, converting them to lowercase for case-insensitive counting.
• A dictionary word_counts is used to store the count of each word.
• The code then iterates through the word_counts dictionary and writes each word and its count to the output file.
• Error handling is included for potential issues during file writing.

Model Answer 2

This solution uses the csv module to read and write CSV files, performing calculations on the data.

import csv

def calculateproductrevenue(inputfilename, outputfilename):

product_revenue = {}

try:

with open(input_filename, 'r', newline='') as infile:

reader = csv.reader(infile)

header = next(reader) # Skip the header row

for row in reader:

product_name, quantity, price = row

try:

quantity = int(quantity)

price = float(price)

except ValueError:

print(f"Warning: Invalid data in row: {row}. Skipping.")

continue

revenue = quantity * price

if productname in productrevenue:

productrevenue[productname] += revenue

else:

productrevenue[productname] = revenue

except FileNotFoundError:

print(f"Error: File '{input_filename}' not found.")

return

try:

with open(output_filename, 'w', newline='') as outfile:

writer = csv.writer(outfile)

writer.writerow(["Product Name", "Total Revenue"]) # Write header

for product, revenue in product_revenue.items():

writer.writerow([product, revenue])

except Exception as e:

print(f"Error writing to file '{output_filename}': {e}")

if name == "main":

inputfile = "salesdata.csv"

outputfile = "productrevenue.csv"

calculateproductrevenue(inputfile, outputfile)

Explanation:

• The code uses the csv module to read the input CSV file.
• It skips the header row.
• For each row, it extracts the product name, quantity, and price.
• It calculates the revenue for that sale.
• It aggregates the revenue for each product in the product_revenue dictionary.
• Finally, it writes the product names and their total revenue to the output CSV file.
• Error handling is included for file not found and invalid data in the input file.