Errors and Exceptions

Question 1

What does the interpreter provide in terms of Error Checking?

Answer 1

• Line Number
• Error Type

Question 2

What is an Exception?

Answer 2

An error that occurs during program execution and disrupts the normal flow of a program

Question 3

Write down a code that mitigates a ZeroDivisionError from user input taken

Answer 3

try:
    value = input()
    result = str(5 / int(value))
    print("Your result is: " + result)
except ZeroDivisionError:
    print("You tried dividing by Zero")

Question 4

Write down a code that mitigates file not found error attempting to read a file

Answer 4

try:
    file_name = input()
    my_file = open(file_name, "r")
    print(my_file.read())
    my_file.close()
except FileNotFoundError:
    print("File not found")
    

Question 5

How to ensure some code runs as part of the try statement regardless of whether or not an exception occurred? Give a simple example.

Answer 5

• You can do this by adding a finally clause to the end of the try/except block
• Code in the finally block will always run after a try/except block regardless of errors

try:
    try:
    value = input()
    result = str(5 / int(value))
    print("Your result is: " + result)
except ZeroDivisionError:
    print("You tried dividing by Zero")
finally:
    print("Here is our final block")
print("End of program")
    

Question 6

How to raise an exception by yourself?

Answer 6

You can do this by using the “raise” command, followed by the exception that you’d like to raise

try:
      raise ZeroDivisionError
finally:

Question 7

If you wanted to add to variables (a + b) but instead wrote (a - b). Which error would be raised? How to fix?

Answer 7

• “logical error”
• Debugging
• Process of finding and fixing logical error

Question 8

What mitigation is there for debugging? How to use it?

Answer 8

• Logging
• Better understanding of application flow
• Improved bug and error tracking.

Question 9

Which levels of severity are in python?

Answer 9

debug
info
warning
error
critical

Question 10

How to create a log entry?

Answer 10

• Logging object, followed by period and level of log entry you wish to create (debug, info, warning, error, critical)
• Followed by log message in parentheses

logging.debug("Debug is the lowest Level in Severity")
logging.critical("Critical is the fifth and highest level")

Question 11

What is Pythons Default logging level?

Answer 11

Warning
Only messages of a level equal to or more severe than the warning level will be logged

Question 12

How to customize the logging function within python?

Answer 12

logging.basicConfig()

Allows you to change:
* Level of log output
* Write logs to files

Question 13

Give an example of how to change logging level

Answer 13

• Set level parameter in the call to basicConfig
  logging.basicConfig(level=logging.DEBUG)

Question 14

Give an example of writing logs to a file

Answer 14

import logging
logging.basicConfig(filename="mylog.log", filemode="w", level=logging.DEBUG)

Question 15

How to customize logs? Explain and give example

Answer 15

You can use various attributes to get more detailed info on what is going on in your program. You set these attributes in the basicConfig function by assigning a string to the format parameter

• format is keyword
• & denotes data type
• asctime is attribute outputting date and time of log creation
• message attribute is placeholder for actual log message

logging.basicConfig(format=%(asctime)s: %(message)s")
logging.critical("My log message")

Question 16

Which line of code will set log level to warning?

Answer 16

logging.basicConfig(level = logging.WARNING)