College Board Big Idea 1

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: 

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.
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 a is the 1 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.
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 c is the 3 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)
evens = []
i = 0

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

print(evens)    

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

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

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.

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)

[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.
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, 100]

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
orderedItems=[]

#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
totalCost=0
totalCost=float(totalCost)
while True:
    item = input("Please select an item from the menu, type \"exit\" to exit")
    item=item.lower()
    try:
        menu[item]
    except:
        if item.lower() == "exit":
            print("Checking out...")
            break
        print(f"Sorry, we don't have {item}")
        continue
    orderedItems.append(item)
    totalCost+=menu[item]

#code should add the price of the menu items selected by the user 
print("┌────────────────────────────┐")
print("│ RECEIPT:                   │")
for item in orderedItems:
    string = "│ " + item + " - " + str(menu[item])
    if item == "burger":
        length = ("              │")
    else:
        length = ("               │")

    print(string + length)
print(f"│ Total - ${str(round(totalCost, 2))}              │")
print("└────────────────────────────┘")

Menu
burger  $3.99
fries  $1.99
drink  $0.99
Sorry, we don't have steak
Checking out...
┌────────────────────────────┐
│ RECEIPT:                   │
│ burger - 3.99              │
│ fries - 1.99               │
│ drink - 0.99               │
│ drink - 0.99               │
│ Total - $7.96              │
└────────────────────────────┘

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.