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Challenge 1: Declaring a Variable

Answer:

val myFirstVariable: Int = 100 

print(myFirstVariable)

Challenge 2: Type Casting

Answer:

val newType: Double = oldType

Quiz 1:

Q1. Variables are used for storing data.

• True
• False

Q2. What role does the variable name play when declaring a variable?

• Decides if the variable is immutable or mutable
• Acts as an identifier for the variable
• Decides the data type of the variable
• Declares the initial value of the variable

Q3. Which print satement should be used for printing on mulitple lines?

• print()
• println()
• Both
• None of the above

Q4. What will be the output of the following code:

val randomNumber: Int = 39
randomNumber = 72
println(randomNumber)

• 39
• 72
• error
• randomNumber

Q5. What is the default type of a Scala Variable?

• Immutable
• Mutable
• Both
• None of the above

Q6. Which subclass does the data type Byte come under?

• AnyVal
• Anyref
• Both
• None of the above

Q7. What is the flow of Scala’s type hierarchy from top to bottom?

• AnyRef to AnyVal
• specific to generic
• AnyVal to AnyRef
• generic to specific

Q8. What is Scalas supertype?

• All
• Each
• Every
• Any

Q9. Which of the following is allowed in terms of type casting?

• Long => Int
• Double => Float
• Short => Int
• Byte => Char

Q10. What are the three requirements for declaring a variable?

• Variable name, Data type, Initial Value
• Keyword, Variable name, Initial Value
• Keyword, Data type, Initial Value
• Keyword, Variable name, Data type

Challenge 3: Using Multiple Operators

Answer:

val compareCheck = check < 75 && check >= 8

Challenge 4: Temperature Conversion

Answer:

val celsius = (fahrenheit - 32) * (5D / 9D)

Quiz 2:

Q1. There are two ways to call a method in Scala.

• True
• False

Q2. Which method call uses the infix notation?

• Ordinary
• Operator
• None of the above
• All of the above

Q3. How many built-in operators does Scala provide?

• 4
• 5
• 6
• None of the above

Q4. What is the difference between ordinary method calls and operator method calls?

• The only difference is the syntax
• Both calls result in different outputs
• None of the above
• All of the above

Q5. Select the correct output for the following code:

val operand1 = 7
val operand2 = 3

println(operand1 / operand2)

• 2.3333333
• 3
• 2
• None of the above

Q6. Select the correct output for the following code:

val operand1 = 's'
val operand2 = 'q'

println(operand1 <= operand2)

• false
• true
• sq
• None of the above

Q7. Select the correct output for the following code:

val A = true
val B = true
val exp = A || B

println(false && exp)

• Exp
• false
• true
• None of the above

Q8. Select the correct output for the following code:

val operand1 = 7
val operand2 = 3

println(operand1 & operand2)

• 3
• 7
• 10
• None of the above

Q9. Select the correct output for the following code:

var operand1 = 7
var operand2 = 3
operand1 += operand2

println(operand1)

• 3
• 7
• 10
• None of the above

Q10. Which of the following is correct in terms of operator precedence?

• <, *, &
• !=, |, ^
• ==, :, ( )
• None of the above

Challenge 5: Embed a Variable in a String

Answer:

print(s"$name is $age years old.")

Challenge 6: Formatting Strings

Answer:

print(f"The quotient is $quotient%.3f")

Challenge 7: Searching a String

Answer:

  val expressionToFind = "[a-z]{3}".r
  val match1 = expressionToFind.findFirstIn(stringToFindExpression)

Quiz 3:

Q1. What is string interpolation?

• Embedding strings with numbers
• Embedding strings with variables
• Embedding strings with expressions
• All of the above
• None of the above

Q2. How many string interpolation methods does Scala provide?

• 2
• 3
• 4
• None of the above

Q3. What are processed string literals?

• Strings that require further processing during run time
• Strings that require further processing during compilation time
• Modified strings
• None of the above

Q4. What would the output be of the given code:

println(s"3 + 2 = ${3 + 2}")

• 5
• 3 + 2 = 5
• ${3+2}
• None of the above

Q5. Which Java method does the f string interpolator represent?

• fprint()
• print()
• printf()
• None of the above

Q6. What would the output be of the given code:

val insertSeparator = 12345678
println(f"$insertSeparator%,d")

• 12,345,678
• 12345678
• 12.345.678
• 12%345%678
• 12 345 678

Q7. What is the difference between the raw string interpolator and the s string interpolator?

• raw recognizes escape sequences while s doesn’t
• raw doesn’t recognize escape sequences while s does
• raw recognizes character literals while s doesn’t
• raw doesn’t recognize character literals while s does
• All of the above
• None of the above

Q8. The split() method can only split at a comma ,.

• True
• False

Q9. What encompasses multiline strings?

• '''
• """"
• """
• None of the above

Q10. What would the output be of the given code:

val regularExp = "[a-z]{4}".r

val replaceIn = "She is four years old "

val replaced = regularExp.replaceFirstIn(replaceIn,"five")

println(replaced)

• She is five years old
• She is four years old
• Error
• None of the above

Challenge 8: Array of Integers

Answer:

val array1 = Array.range(minRange, maxRange)
val array2 = array1.map(_ * 3)
val finalArray = array2.filter(_ % 2 == 0)

Challenge 9: Appending an Element to a List

Answer:

val finalList = list :+ list(0)

Quiz 4:

Q1. How many collection classes are at the top of the collection library?

• 2
• 3
• 4
• None of the above
• All of the above

Q2. What is the difference between an immutable and mutable collection?

• An immutable collection cannot be updated while a mutable collection can be updated
• To update an immutable collection, a new collection is created with the updated values
• To update a mutable collection, values are updated in the original collection
• All of the above
• None of the above

Q3. Which collection class does not store a single value more than once?

• set
• map
• seq
• All of the above
• None of the above

Q4. Choose the correct syntax for the foreach method.

• method.foreach(collection)
• collection.method(foreach)
• collection.foreach(method)
• All of the above
• None of the above

Q5. What will be the output of the following code:

val array1 = Array(1,2,3,4,5)
val array2 = array1.map(_ * 5)
val finalArray = array2.filter(_ % 2 != 0)
finalArray.foreach(println)

• 10 20
• 5 15 25
• 1 2 3 4 5
• 5 10 15 20 25
• None of the above

Q6. What will be the output of the following code:

val list1 = 39::27::1::83::Nil
val finalList = 5 +: list1
finalList.foreach(println)

• 39 27 1 83
• 39 27 1 83 5
• 44 32 6 88
• 5 39 27 1 83
• None of the above

Q7. What is the difference between a Vector and a List?

• Lists are linear while Vectors are indexed
• Vectors are linear while Lists are indexed
• Vectors are a mutable seq type collection and Lists are an immutable seq type collection
• Lists are a mutable seq type collection and Vectors are an immutable seq type collection
• All of the above
• None of the above

Q8. The following expressions use the Range collection. Which one is incorrect?

• Option 1

10 to 20

• Option 2

10 to 20 by 5

• Option 3

20 from 10

• Option 4

10 until 20

• All of the above
• None of the above

Q9. Why is a Stream called a lazy List?

• They are created using #:: instead of ::
• Streams can be infinitely long
• Streams only compute required elements
• All of the above
• None of the above

Challenge 10: Pass or Fail

Answer:

if (percentage >= 60) 
  print("pass")
else 
  print("fail")

Challenge 11: Oven is Ready!

Answer:

while (temperature<375) { 
  temperature += 25
  count +=1
}

Challenge 12: Array of Squares

Answer:

for (i <- 0 until testArray.length) {
  testArray(i) = testArray(i) * testArray(i)
}

Challenge 13: Color Wheel

Answer:

testVariable match {
  case "blue" => print("orange")
  case "yellow" => print("purple")
  case "red" => print("green")
  case _ => print("not a primary color")
}

Quiz 5:

Q1. What are control structures used for?

• Control structures are used for determining the output of a statement
• Control structures dictate the flow in which statements are executed
• Control structures are diagrams used for understanding the flow of execution
• All of the above
• None of the above

Q2. Which statements regarding imperative and declarative programming are true? (Multiple correct answers)

• Imperative programming is how to execute a sequence of code and declarative programming is what a sequence of code should do.
• Declarative programming is how to execute a sequence of code and imperative programming is what a sequence of code should do.
• Functional programming is a subset of imperative programming.
• Functional programming is a subset of declarative programming

Q3. Which statement is depictive of imperative programming?

• Restart your computer at 5pm
• Meet me at the movies at 8pm with Sarah and Ben
• Go to my room and open the closet; you will find the sweater on the right end.
• All of the above
• None of the above

Q4. How many control structures does Scala provide?

• 4
• 5
• 6
• None of the above

Q5. How does Scala bring a functional approach to imperative control structures?

• In Scala, control structures return values just like functions.
• In Scala, control structures are functions themselves.
• In Scala, control structures take arguments like functions.
• All of the above
• None of the above

Q6. What will be the output of the following code:

val array = Array(1,2,3,4,5)

for (i <- 0 until array.length) {
  if (array(i) % 2 == 0) {
    println(array(i))
  }
}

• 1 2 3 4 5
• 1 3 5
• There will be no output
• 2 4
• None of the above

Q7. What will be the output of the following code:

val constantPattern: Any = List()

constantPattern match {
  case 5 => print("five")
  case true => print("truth")
  case "hello" => print("hi!")
  case Nil => print("the empty list")
  case _ => print("something else")
} 

• something else
• the empty list
• true
• None of the above

Q8. What will be the output of the following code:

val sequencePattern = Array(1,2,0)

sequencePattern match {
  case Array(0,_,_)  => println("case1")
  case Array(1,_,_)  => println("case2")
  case Array(_,_,0)  => println("case3")
  case _ => println("default")
}

• case3
• case1
• case2
• case2 case3
• None of the above

Q9. while is an expression.

• True
• False

Q10. How is while different from the other control structures?

• Unlike the other control structures, it is not an expression.
• Unlike the other control structures, it doesn’t have a return value.
• In Scala, the other control structures are preferred over while.
• All of the above
• None of the above

Challenge 14: Absolute Value

Answer:

def absolute(x: Double): Double = {
  if (x < 0) -x else x
}

Quiz 6: CBV or CBN?

Q1. evaluate(2,3)

• CBV
• CBN
• same

Q2. evaluate(3+4, 8)

• CBV
• CBN
• same

Q3. evaluate(7, 2*4)

• CBV
• CBN
• same

Challenge 15: Sum of Lists

Answer:

//Solution using match
def sum(numberList: List[Int]): Int = numberList match { 
  case Nil => 0
  case x :: tail => x + sum(tail)
}

Challenge 16: Max with Nested Functions

Answer:

def mainMax(a: Int, b: Int, c: Int): Int = {
  def max(x: Int, y: Int) = {
    if(x > y) x
    else y
  }
  max(a,max(b,c))
}

Challenge 17: Tail Recursion

Answer:

def factorial(x: Int): Int = {
  def loop(accumulator: Int, x: Int): Int = {
    if(x==0) accumulator
    else loop(accumulator*x,x-1)
  }
  loop(1,x)
}

Quiz 7:

Q1. Which keyword is used for defining a function?

• val
• var
• def
• None of the above

Q2. The following are optional when defining a basic function.

• function body wrapped in curly brackets and return type of the function
• parameters wrapped in parenthesis and return type of the function
• parameter type and function body wrapped in curly brackets
• parameters wrapped in parenthesis and parameter type
• None of the above

Q3. What is the basic idea of the substitution model?

• Evaluation only reduces an expression to a value if it is being used
• Evaluation reduces expressions to a value.
• Evaluation reduces a functions arguments to a value
• All of the above
• None of the above

Q4. What purpose do CBV and CBN have?

• They dictate which expressions should be evaluated
• They dictate the order in which expressions are to be evaluated
• They determine which expressions are to be terminated
• All of the above
• None of the above

Q5. If the CBN evaluation of an expression terminates, then the CBV evaluation of the same expression is not guaranteed to terminate.

• True
• False

Q6. What does the following recursive function do?

def mysteryFunction(list: List[Int]): Int = { 
  def mysteryAccum(list: List[Int], theMystery: Int): Int = {
    list match {
      case Nil => theMystery
      case x :: tail =>
        val newMystery = if (x > theMystery) x else theMystery
        mysteryAccum(tail, newMystery)
    }
  }
  mysteryAccum(list, 0)
}

• returns the minimum value in a given list
• returns the median (middle value) in a given list
• returns the maximum value in a given list
• error
• All of the above
• None of the above

Q7. What is the general purpose of Newton’s method?

• Finding the square root of a number
• Approximating the square root of a number using improved estimates
• Approximating solutions using an iterative process
• All of the above
• None of the above

Q8. Which function definition will give an error?

• Option 1

def factorial(x: Int) = {
  def loop(accumulator: Int, x: Int): Int = {
    if(x==0) accumulator
    else loop(accumulator*x,x-1)
  }
  loop(1,x)
}

• Option 2

def factorial(x: Int): Int = {
  def loop(accumulator: Int, x: Int) = {
    if(x==0) accumulator
    else loop(accumulator*x,x-1)
  }
  loop(1,x)
}

• Option 3

def factorial(x: Int): Int = {
  def loop(accumulator: Int, x: Int): Int = {
    if(x==0) accumulator
    else loop(accumulator*x,x-1)
  }
  return loop(1,x)
}

• All of the above
• None of the above

Q9. What is the benefit of lexical scoping?

• Removes redundant code
• Makes definitions outside a block visible to definitions inside a block
• Permits variable shadowing
• All of the above
• None of the above

Q10. Which of the following is a tail recursive function?

• Option 1

def fib(x: Int): BigInt = {
  def fibHelper(x: Int, prev: BigInt = 0, next: BigInt = 1): BigInt = x match {
    case 0 => prev
    case 1 => next
    case _ => fibHelper(x - 1, next, (next + prev))
   }
   fibHelper(x)
  }

• Option 2

def sum(ints: List[Int]): Int = ints match { 
  case Nil => 0
  case x :: tail => x + sum(tail)
  }

• Option 3

def factorial(n: Int): Int = { 
  if (n == 0) 1
  else n * factorial(n-1)
} 

• All of the above
• None of the above

Q11. Which of the following statements is true for blocks?

• When you define something inside a block, it is only visible from within the block.
• The definitions inside a block, shadow definitions of the same names outside the block.
• You can define a variable inside a block with the same name as a variable outside a block without it affecting the outside variable.
• All of the above
• None of the above

Challenge 18: Write your First Higher-Order Function

Answer:

def arithmeticPrinter(f: (Int , Int) => Int, x: Int, y: Int) = {
    
  print(f(x,y))
}

Challenge 19: Anonymous Functions

Answer:

def arithmeticPrinter(f: (Int,Int) => Int, x: Int, y: Int) = {
  print(f(x,y))
} 

def printAdd(x: Int, y: Int) = {
  arithmeticPrinter((x,y) => x+y, x, y)
}

def printSubtract(x:Int, y: Int) = {
  arithmeticPrinter((x,y) => x-y, x, y)
}

Challenge 20: Using a Curried Function

Answer:

def product(f: Int => Int)(a: Int, b: Int): Int ={
  if(a > b) 1
  else f(a) * product(f)(a+1,b)
}

def fact(n: Int) = product(x=>x)(1,n)

Quiz 8:

Q1. What does it mean for a function to be treated as a first-class value?

• A function can be passed as a parameter.
• A function can be returned as a result
• A function is treated like a basic data value such as an integer
• All of the above
• None of the above

Q2. The code snippets below are using functions as function parameters. Which of the following will result in a syntax error?

• Option 1

def func1(f: Int => Int, x: Int) = {
  print(f(x))
}

• Option 2

def func2(f: Int => Int, x: Int) = {
  print(f)
}

• Option 3

def func3(x: Int, f: Int => Int) = {
  print(f(x))
}

• Option 4

def func4(f: (Int,Int) => Int, x: Int, y: Int) = {
  print(f(x,y))
}

• All of the above
• None of the above

Q3. The code snippets below are anonymous functions which return the product of two numbers. Which of the following are the incorrect implementation?

• Option 1

(x,y) => x*y

• Option 2

x,y => x*y

• Option 3

(x:Int, y:Int) => x*y

• All of the above
• None of the above

Q4. What is syntactic sugar?

• Syntax that makes code easier to read and express
• Syntax which changes the functionality of the code
• It’s just a cool way of saying ‘sweet syntax!’
• All of the above
• None of the above

Q5. Anonymous functions are syntatic sugar because they don’t bring any change to the expressive power of Scala.

• True
• False

Q6. The function saySomething, returns an anonymous function. What will be the output of the following code?

def saySomething(prefix: String) = (s: String) => {
  prefix + " " + s
}

def saySomethingElse = saySomething("hello")

print(saySomethingElse("there"))

• hellothere
• therehello
• hello there
• hello
• there
• None of the above

Q7. What is currying?

• A way of returning functions
• A way of writing functions with multiple parameter lists
• The art of making a delicious curry
• All of the above
• None of the above

Q8. add is a curried function. What will be the output of the follwoing code?

def add(a: Int)(b: Int) = a + b

val first = add(1)(5) 

val second = add(4)_ 

val third = second(2) 

print(first == third) 

• 6
• 4
• 2
• true
• false
• None of the above

Quiz 9:

Q1. A bluprint is used to create identical copies of the same object.

• True
• False

Q2. The members of a class can be divided into the following two parts:

• methods and variables
• functions and properties
• methods and properties
• All of the above
• None of the above

Q3. Why is an object known as an instance of a class?

• Just a naming convention.
• An object is an instantiated class.
• An instance a singular occurence of something the same way an object is a single occurence of a class.
• All of the above
• None of the above

Q4. The code below declares a EqualShape class and creates its instance sqaure. Why will the code not compile?

class EqualShape{
  var numOfSides: Int = 0
  var lengthOfSides: Int = 0

  def perimeter = numOfSides * lengthOfSides
}

val square = EqualShape 

• The code will compile
• Incorrect object declaration
• Incorrect class declaration
• Members of the class are incorrectly defined
• None of the above

Q5. What will be the output of the following code?

class EqualShape{
  var numOfSides: Int = 0
  var lengthOfSides: Int = 0

  def perimeter = numOfSides * lengthOfSides
}

val square = new EqualShape
val triangle = new EqualShape 
square.numOfSides = 4
square.lengthOfSides = 5

print(triangle.perimeter)

• 0
• 20
• Error
• None of the above

Q6. When we can pass arguments to an object class, this means that the class was defined using…

• constructor parameters
• constructors
• members
• All of the above
• None of the above

Q7. What will be the output of the follwoing code?

class Point(xc: Int, yc: Int) {
  var x: Int = xc
  var y: Int = yc

  def move(dx: Int, dy: Int) {
    x = x + dx
    y = y + dy
    println ("Point x location : " + x);
    println ("Point y location : " + y);
   }
}

val point = new Point(5, 10)

point.move(point.x+1, point.y+2)

• Point x location : 5 Point y location : 10
• Point x location : 6 Point y location : 12
• Point x location : 11 Point y location : 22
• Point x location : 1 Point y location : 2
• None of the above

Q8. What is the difference bewteen a singleton object and a class?

• A singleton object is created using the object keyword while a class is created using the class keyword.
• A singleton object only has a single instance, unlike a class which has multiple instances.
• A singleton object cannot be created using the new keyword while a class object must be created using the new keyword.
• All of the above
• None of the above

Q9. A companion object can access private members of its companion class.

• True
• False

Q10. What is the use of stand alone objects?

• They are used as an entry point of a Scala application.
• They are used to execute programs.
• They can be used anywhere in the program, hence, allow easy access.
• All of the above
• None of the above

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