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 # AP Video Notes # Video #1:- Logic Error: Algorithmic mistake- Syntax Error: language mistakes, not following language rule

Runtime Error: Program Crashes, "bug", cannot complete process, /0, wrong data type, forever loop

Overflow Error, not enough memory # Video #2:

Syntax Errors are the easiest to debug, as the output shows where the error is

Logic errors are hard to notice, make testcases that work/don't work, border cases

hand tracing can be useful with loops

Use debuggers and/or print statements # Video #3:

"How will we know if a program is working properly" - program specifications

try corner and border cases to make sure that it will work

test, find mistakes, edit, update. # Proof:

Here are some code segments you can practice fixing:

alphabet = "abcdefghijklmnopqrstuvwxyz"

alphabetList = []

for i in alphabet:
    alphabetList.append(i)

print(alphabetList)

['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']

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. # My fix: I printed i+1, as each letter was one less that it should have been

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+1) + " letter in the alphabet")
    i += 1

The letter z is the 26 letter in the alphabet

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. # My Fix: I did the same as before, and moved the initialization of the Count

letter = input("What letter would you like to check?")
count = 0
for i in alphabetList:
    if i == letter:
        print("The letter " + letter + " is the " + str(count+1) + " letter in the alphabet")
    count += 1

The letter x is the 24 letter in the alphabet

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) # My Fix: Changed the initial value of i from 0 to 1

evens = []
i = 1

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

print(evens)

[1, 3, 5, 7, 9]

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

See Above

odds = []
i = 1

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

print(odds)

[1, 3, 5, 7, 9]

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)

[0, 2, 4, 6, 8, 10]

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

My Fix:

I checked the remainder when divided by 2 to be 1 rather than 0

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

for i in numbers:
    if (numbers[i] % 2 == 1):
        odds.append(numbers[i])

print(odds)

[1, 3, 5, 7, 9]

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. # My Fix: Change if for the remainder with five to elif

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])
    elif numbers[i] % 2 == 0:
        newNumbers.append(numbers[i])

print(newNumbers)

[0, 2, 4, 5, 6, 8, 10, 12, 14, 15, 16, 18, 20, 22, 24, 25, 26, 28, 30, 32, 34, 35, 36, 38, 40, 42, 44, 45, 46, 48, 50, 52, 54, 55, 56, 58, 60, 62, 64, 65, 66, 68, 70, 72, 74, 75, 76, 78, 80, 82, 84, 85, 86, 88, 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")
while item != "stop":
    total += menu[item]
    #print(total)
    item = input("Please select an item from the menu")

#code should add the price of the menu items selected by the user 
print("$",round(total,3))

Menu
burger  $3.99
fries  $1.99
drink  $0.99
$ 6.97

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.