Discussion 2:

Functions + Control

Course Website: cs10.org

�Grab a worksheet!

We’ll start at 4:12

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Begin the group activity on the worksheet!

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Question of the Day

Ask the person to your right / left about their opinions on the consumption of caffeine. Do you have it? If so, how much? Do you have coffee, tea, energy drinks, etc.?

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• The average cup of coffee has 95mg of caffeine.
• The effects of 95mg of caffeine can last between 4 to 6 hours
• Caffeine can affect sleep too, by reducing the:
• Total sleep time
• Deep sleep amount of time
• Sleep efficiency

Agenda

• iClicker
• Join in small groups
• Work on Section I
• Go over Questions in Big Group
• Work on Section II
• Go over Questions in Big Group
• Work on Section III
• Go over Questions in Big Group
• Q&A + Feedback Form

Logging into iClicker

• 4-5PM Discussion (Soda 438)
• Enroll into join.iclicker.com/ZNLT

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• 5-6PM Discussion (Stanley 106)
• Enroll into join.iclicker.com/YRIL

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Questions + Comments from Feedback Form

• What do I do if I miss lab
• whats some cool ideas for custom blocks one can create?

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Worksheet Time!

Section I - Fucntions

Section I - Functions

1. What will the following return? Why?

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Section I - Functions

• What will the following return? Why?

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False, because the data types are different. The left “true” is a boolean data type and the right is text.

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Section I - Functions

• What will the following return? Why?

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Defining Data Types, Domain, Range

• What’s a data-type? Why is it useful to know the data-type of a variable?
• What does domain mean in the context of data-types? How do we figure out the domain of a Snap! block?
• What does range mean in the context of data-types? How do we figure out the range of a Snap! Block?

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Question 2

• What’s a data-type, and why is it useful to know?
• A restriction / classification on a value
• Can be helpful if we only want certain types of data!
• What does domain mean in the context of data-types? How do we figure out the domain of a Snap! Block?
• Domain is the data type of the input / parameter passed in
• We can figure it out by looking at the parameter shape
• What does range mean in the context of data-types?
• Range is the is the data type of the output / returned value
• We can figure it out by looking at the shape of the block

Restricting Data Types in Snap!

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Number

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Text (string)

Boolean

List

Function

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Can be anything! No restrictions

Q3: What are the data types, domain, range of each function:

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What are the data types, domain, range of each function:

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Q4: What are the data types of each function:

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Q4: What are the data types of each function:

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Section II - Variables

Guess that Scope!

Guess that Scope!

Reports: 10

Guess that Scope!

Guess that Scope!

Reports: 10

Guess that Scope!

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Guess that Scope!

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Reports: 20

a = 10, b = 10

Guess that Scope!

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Guess that Scope!

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Reports: 10

a = 20, b = 10

Section III - Control Structures

Boolean + Truth Tables

Boolean + Truth Tables

Boolean + Truth Tables

True

True

False

False

True

True

False

False

True

True

False

False

True

True

False

False

Boolean + Truth Tables

True

True

False

False

True

True

False

False

True

True

False

False

True

True

False

False

True and True

True and False

False and True

False and False

True or True

True or False

False or True

False or False

Boolean + Truth Tables

True

True

False

False

True

True

False

False

True

True

False

False

True

True

False

False

True

False

False

False

True

True

True

False

Boolean + Truth Tables

Boolean + Truth Tables

Boolean + Truth Tables

Boolean + Truth Tables

Boolean + Truth Tables

Boolean + Truth Tables

Boolean + Truth Tables

Boolean + Truth Tables

What will the following return?

What will the following return?

T

T

T

T

T

T

T

T

T

What will the following return?

T

T

T

What will the following return?

T

T

F

Because this is False the line doesn’t get run

What will the following return?

T

T

F

T

Evaluate

What will the following return?

T

T

F

F

Because this is False the line doesn’t get run

What will the following return?

T

T

F

T

T

Because this is True, we evaluate

F

What will the following return?

T

T

F

T

T

T

T

Not (T and T)

F

What will the following return?

T

T

F

T

T

T

Not (T and T)

F

What will the following return?

T

T

F

T

T

T

Not (T)

F

What will the following return?

T

T

F

T

T

T

F → so mystery(True, True) returns False

F

F

Will this ever return true?

Conditionals: Can this ever return True?

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Determine with Option 1: Draw it out / Walk through it with the logic of the code

Conditionals: Can this ever return True?

• If ‘a’ is T, not a, will be false

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• This statement is only evaluated then if ‘a’ is F → (not F) → T

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Conditionals: Can this ever return True?

• If ‘a’ is T, not a, will be false

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• This statement is only evaluated then if ‘a’ is F → (not F) → T

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• So, if ‘a’ is F, then what should ‘b’ have to make (‘a’ and ‘b’) return T?

Conditionals: Can this ever return True?

• If ‘a’ is T, not a, will be false

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• This statement is only evaluated then if ‘a’ is F → (not F) → T

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• So, if ‘a’ is F, then what should ‘b’ have to make (‘a’ and ‘b’) return T?

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• It can never return T!

Conditionals: Can this ever return True?

• For ‘b’ = F to be true, we need ‘b’ to be set to F (because F = F is True)

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Conditionals: Can this ever return True?

• What value of ‘b’ would make this statement true?

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• Hint: Look at your truth table!

Conditionals: Can this ever return True?

• For ‘b’ = F to be true, we need ‘b’ to be set to F (because F = F is True)

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Conditionals: Can this ever return True?

• For ‘b’ = F to be true, we need ‘b’ to be set to F (because F = F is True)

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• What value of ‘a’ would make ((not a) = T) return True?

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Conditionals: Can this ever return True?

• For ‘b’ = F to be true, we need ‘b’ to be set to F (because F = F is True)

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• What value of ‘a’ would make ((not a) = T) return True?

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• If ‘a’ is F

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Conditionals: Can this ever return True?

• For ‘b’ = F to be true, we need ‘b’ to be set to F (because F = F is True)

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• What value of ‘a’ would make ((not a) = T) return True?

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• If ‘a’ is F

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• But wait, didn’t we already try that here?

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Conditionals: Can this ever return True?

• But wait, didn’t we already try that here?

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• We did! And, when ‘a’ was False, the statement was evaluated and the function returned False

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Conditionals: Can this ever return True?

• This if statement gets run before the else if, even though both statements return True

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• We already established that the first if statement always returns True.

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• The else if statement, even if it could technically return, True, will never get evaluated

Conditionals: Can this ever return True?

• So, this else if statement either never gets evaluated because the statement evaluates to False or the function terminated from the previous statement

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• Or, the statement does get evaluated and then the report

< (not a) = true >

will always return False

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Conditionals: Can this ever return True?

• Else if <True> (with the green check mark) is the same as an else statement.

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• Meaning, the statement will always be evaluated if the above statements were not evaluated

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• For what values of ‘a’ and ‘b’ would the expression return True

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Conditionals: Can this ever return True?

• For what values of ‘a’ and ‘b’ would the expression return True: There’s a few!

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• But, we have the same problem as earlier.

Conditionals: Can this ever return True?

• So the function never returns True!

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Conditionals: Can this ever return True?

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Determine with Option 2: Try all the True and False values for a and b, and see what gets outputted

Conditionals: Can this ever return True?

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Determine with Option 3: Determine based on the truth table (but I find this way a little hard to read personally)

Truth Table

Conditionals

Conditionals

Conditionals

Conditionals

Conditionals

Conditionals

Conditionals

Conditionals

Conditionals

Conditionals

Conditionals

Conditionals

Conditionals

Conditionals

Conditionals: Blue = Statements, Red = Return Values

Conditionals: Yellow = Currently looking at values

• Won’t be evaluated, since not A is F

Conditionals: Can this ever return True?

• Won’t be evaluated, since not A is F

Conditionals: Can this ever return True?

• Don’t care about these values since they return F

Conditionals: Can this ever return True?

• Don’t care about these values since they return F

Conditionals: Can this ever return True?

• Don’t care about these values since they return F

Conditionals: Can this ever return True?

• Won’t be evaluated because b = False is False when b is False

Conditionals: Can this ever return True?

• This one is the trickiest.

Conditionals: Can this ever return True?

This is T and returns T, but the previous if statement was also T and returned F

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Conditionals: Can this ever return True?

• This if statement gets run before the else if, even though both statements return True

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• We already established that the first if statement always returns True.

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• The else if statement, even if it could technically return, True, will never get evaluated

Conditionals: Can this ever return True?

This is T and returns T, but the previous if statement was also T and returned F

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Conditionals: Can this ever return True?

• Returns False, so we can get rid of it

Conditionals: Can this ever return True?

Similarly, True statements were already evaluated and returned False

Conditionals: Can this ever return True?

So these are never evaluated either

Conditionals: Can this ever return True?

• Returns False, so we can get rid of it

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Conditionals: Can this ever return True?

• So this function never returns True!

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Q&A + Feedback Form

• Link: tinyurl.com/fa25-disc-form

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See you next week!