Identifying and Correcting Errors (Unit 1.4)

Become familiar with types of errors and strategies to fixing them

Lightly Review Videos and take notes on topics with Blog

Complete assigned MCQ questions

Here are some code segments you can practice fixing:

#Create a list of the alphabet

alphabet = "abcdefghijklmnopqrstuvwxyz"

alphabetList = []

for i in alphabet:
    alphabetList.append(i)

print(alphabetList)

The intended outcome is to determine where the letter is in the alphabet using a while loop

What is a good test case to check the current outcome? Why?
Make changes to get the intended outcome.

letter = input("What letter would you like to check?")

i = 0

while i < 26:
    if alphabetList[i] == letter:
        print("The letter " + letter + " is the " + str(i) + " letter in the alphabet")
    i += 1

---------------------------------------------------------------------------

KeyboardInterrupt                         Traceback (most recent call last)

Cell In[1], line 8
      5 i = 0
      7 while i < 26:
----> 8     if alphabetList[i] == letter:
      9         print("The letter " + letter + " is the " + str(i) + " letter in the alphabet")
     10     i += 1


Cell In[1], line 8
      5 i = 0
      7 while i < 26:
----> 8     if alphabetList[i] == letter:
      9         print("The letter " + letter + " is the " + str(i) + " letter in the alphabet")
     10     i += 1


File _pydevd_bundle/pydevd_cython.pyx:1457, in _pydevd_bundle.pydevd_cython.SafeCallWrapper.__call__()


File _pydevd_bundle/pydevd_cython.pyx:701, in _pydevd_bundle.pydevd_cython.PyDBFrame.trace_dispatch()


File _pydevd_bundle/pydevd_cython.pyx:1152, in _pydevd_bundle.pydevd_cython.PyDBFrame.trace_dispatch()


File _pydevd_bundle/pydevd_cython.pyx:1135, in _pydevd_bundle.pydevd_cython.PyDBFrame.trace_dispatch()


File _pydevd_bundle/pydevd_cython.pyx:312, in _pydevd_bundle.pydevd_cython.PyDBFrame.do_wait_suspend()


File ~/anaconda3/lib/python3.11/site-packages/debugpy/_vendored/pydevd/pydevd.py:2070, in PyDB.do_wait_suspend(self, thread, frame, event, arg, exception_type)
   2067             from_this_thread.append(frame_custom_thread_id)
   2069     with self._threads_suspended_single_notification.notify_thread_suspended(thread_id, thread, stop_reason):
-> 2070         keep_suspended = self._do_wait_suspend(thread, frame, event, arg, suspend_type, from_this_thread, frames_tracker)
   2072 frames_list = None
   2074 if keep_suspended:
   2075     # This means that we should pause again after a set next statement.


File ~/anaconda3/lib/python3.11/site-packages/debugpy/_vendored/pydevd/pydevd.py:2106, in PyDB._do_wait_suspend(self, thread, frame, event, arg, suspend_type, from_this_thread, frames_tracker)
   2103         self._call_input_hook()
   2105     self.process_internal_commands()
-> 2106     time.sleep(0.01)
   2108 self.cancel_async_evaluation(get_current_thread_id(thread), str(id(frame)))
   2110 # process any stepping instructions


KeyboardInterrupt: 

The intended outcome is to determine where the letter is in the alphabet using a for loop

What is a good test case to check the current outcome? Why?
Make changes to get the intended outcome.

letter = input("What letter would you like to check?")

for i in alphabetList:
    count = 0
    if i == letter:
        print("The letter " + letter + " is the " + str(count) + " letter in the alphabet")
    count += 1

This code outputs the even numbers from 0 - 10 using a while loop.

Analyze this code to determine what can be changed to get the outcome to be odd numbers. (Code block below)

evens = []
i = 0

while i <= 10:
    evens.append(i)
    i += 2

print(evens)    

This code should output the odd numbers from 0 - 10 using a while loop.

odds = []
i = 0

while i <= 10:
    odds.append(i)
    i += 2

print(odds)

This code outputs the even numbers from 0 - 10 using a for loop.

Analyze this code to determine what can be changed to get the outcome to be odd numbers. (Code block below)

numbers = [0,1,2,3,4,5,6,7,8,9,10]
evens = []

for i in numbers:
    if (numbers[i] % 2 == 0):
        evens.append(numbers[i])

print(evens)

This code should output the odd numbers from 0 - 10 using a for loop.

numbers = [0,1,2,3,4,5,6,7,8,9,10]
odds = []

for i in numbers:
    if (numbers[i] % 2 == 0):
        odds.append(numbers[i])

print(odds)

The intended outcome is printing a number between 1 and 100 once, if it is a multiple of 2 or 5

What values are outputted incorrectly. Why?
Make changes to get the intended outcome.

numbers = []
newNumbers = []
i = 0

while i < 100:
    numbers.append(i)
    i += 1

for i in numbers:
    if numbers[i] % 5 == 0:
        newNumbers.append(numbers[i])
    if numbers[i] % 2 == 0:
        newNumbers.append(numbers[i])

print(newNumbers) 

[0, 0, 2, 4, 5, 6, 8, 10, 10, 12, 14, 15, 16, 18, 20, 20, 22, 24, 25, 26, 28, 30, 30, 32, 34, 35, 36, 38, 40, 40, 42, 44, 45, 46, 48, 50, 50, 52, 54, 55, 56, 58, 60, 60, 62, 64, 65, 66, 68, 70, 70, 72, 74, 75, 76, 78, 80, 80, 82, 84, 85, 86, 88, 90, 90, 92, 94, 95, 96, 98]

Challenge

This code segment is at a very early stage of implementation.

What are some ways to (user) error proof this code?
The code should be able to calculate the cost of the meal of the user

Hint:

write a “single” test describing an expectation of the program of the program
test - input burger, expect output of burger price
run the test, which should fail because the program lacks that feature
write “just enough” code, the simplest possible, to make the test pass

Then repeat this process until you get program working like you want it to work.

menu =  {"burger": 3.99,
         "fries": 1.99,
         "drink": 0.99}
total = 0

#shows the user the menu and prompts them to select an item
print("Menu")
for k,v in menu.items():
    print(k + "  $" + str(v)) #why does v have "str" in front of it?

#ideally the code should prompt the user multiple times
item = input("Please select an item from the menu")

total = total + v
#code should add the price of the menu items selected by the user 
print(total)

Menu
burger  $3.99
fries  $1.99
drink  $0.99


0.99

Hacks

Now is a good time to think about Testing of your teams final project…

What errors may arise in your project?

What are some test cases that can be used?

Make sure to document any bugs you encounter and how you solved the problem.

What are “single” tests that you will perform on your project? Or, your part of the project?

As Hack Design and Test plan action … Divide these “single” tests into Issues for Scrum Board prior to coding. FYI, related tests could be in same Issue by using markdown checkboxes to separate tests.

1.4 Correcting errors • 16 min read

Description

Identifying and Correcting Errors (Unit 1.4)

Here are some code segments you can practice fixing:

Challenge

Hacks