3.3 Video 1 Hacks

Show two examples and label which one is sequence, selection, iteration

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

for i in numbers: #Iteration + Sequencing
    if (numbers[i] % 2 == 0): #Selection + Sequencing
        evens.append(numbers[i]) #Selection + Sequencing

print(evens) # Sequencing

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

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

for i in numbers: #Iteration + Sequencing
    if (numbers[i] % 2 != 0): #Selection + Sequencing
        odds.append(numbers[i]) #Selection + Sequencing

print(evens) # Sequencing

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

Answers 1

All the steps combined are sequencing

The step "for i in numbers:" is iteration because they go through all the numbers.

"if (numbers[i] % 2 == 0)" is selection because they sort each number to find the even ones.

i = 1
starString = "*"
while i <= 5:
  j = 1
  while j <= i:
    print ("*", end= "")
    j += 1
  print ()
  i += 1

*
**
***
****
*****

Answers 2

All the steps are a sequence

"While i <= 5:" is iteration because they repeat until i reaches 5

"While j <= i:" is selection because this is where they decide what j is

3.3 Video 2 Hacks

Practice Problems

  1. given the following code segment below:

a ⟵ 7

b ⟵ 1

c ⟵ 3

d ⟵ 4

a ⟵ b

b ⟵ c + d

d ⟵ b

find the value for a, b, c, d

a = 1, b = 7, c = 3, d = 7

  1. consider the following code segment:

hot ⟵ true

cold ⟵ false

cold ⟵ hot

hot ⟵ cold

what are the values of hot and cold after executing the code segment?

  1. the value of hot is true, the value of cold is true
  2. the value of hot is false, the value of cold is true
  3. the value of hot is true, the value of cold is false
  4. the value of hot is false, the value of cold is false

The answer is 1

  1. Make TWO of your own code segments that contain at least 5 defined variables, then provide the answer and EXPLAIN why your answer is correct.

dogs ⟵ false

cats ⟵ true

parrots ⟵ dogs

dogs ⟵ cats

cats ⟵ parrots

  • dogs: true
  • cats: false
  • parrots: false Dogs is true because it is set to cats, and cats at that time was true. Parrots is false because it is set to dogs, before dogs was set to cats, making it false. Cats is also false because it is set to parrots, which is false, at the very end.

numPups = 0 numCats = 40 numParrots = 10

numCats ⟵ numParrots/10 numParrots ⟵ numCats/10 numPups ⟵ numCats+numParrots numCats ⟵ numParrots/numCats numParrots ⟵ numCats+numPups

  • numPups: 5
  • numCats: 5
  • numParrots: 10 numPups is equal to 5, because it is equal 40/10+10/10, or 5. numCats is 5 because 5/1 = 5 as well. numParrots is set to 5+5 at the very end, making it 10.
  1. Sequencing
num1 = 3
num2 = 1
num3 = 5
num1 = num2 + num3      
num2 = num1 + num3      # num2 is now the new num1 + num3

What is the value of num1 and num2?

num1 = 6, num2 = 11

3.3 Video 3 Hacks

3.4 Video 1 Hacks

String Homework

  • Test 1

    firstName <- "Bob" lastName <- "Smith" var <- substring(firstName, 1, 1) name <- concat(lastName, var) email <- concat(name, "@gmail.com") DISPLAY(email)

  • What would the result be?

    Hint: var = "B" name = "SmithB" ## Test 1: "SmithB(At symbol it does not work)gmail.com"

  • Test 2

    word1 <- "computer" word2 <- "textbooks" length1 <- len(word1)/2 length2 <- len(word2)/3 first <- substring(word1, 2, len1) second <- substring(word2, len2+3, len2) newWord <- concat(first, second) DISPLAY(newWord)

Test 2: "ompuook"