Deck 6: Repetition

Question 1

_________calculate the number of elements in lists.

A) Sentinels
B) Counter variables
C) Accumulators
D) Nested loops

Answer 1

Counter variables

Question 2

A variable declared inside a Do loop cannot be referred to outside of the loop.

Answer 2

True

Question 3

What is wrong with the following simple password program where today's password is "intrepid"
Private Sub btnDisplay_Click(...) Handles btnDisplay.Click Dim password As String
password = InputBox ("Enter today's password:")
Do
lstBox. Items. Add ("Incorrect")
password = InputBox ("Enter today's password:")
Loop Until password = "intrepid"
lstBox. Items. Add ("Password Correct. You may continue.")
End Sub

A) There is no way to re-enter a failed password.
B) The Loop Until condition should be passWord <> "intrepid".
C) It will display "Incorrect." even if the first response is "intrepid".
D) Nothing

Answer 3

It will display "Incorrect." even if the first response is "intrepid".

Question 4

A loop written using the structure Do While...Loop can usually be rewritten using the structure Do...Loop Until.

Question 5

What numbers will be displayed in the list box by the following code when the button is clicked?
Private Sub btnDisplay_Click(...) Handles btnDisplay.Click
Dim num As Integer = 7
Do
num += 1
lstBox.Items.Add(num)
Loop Until (num > 6)
lstBox.Items.Add(num)
End Sub

A) 7
B) 8
C) 7 and 8
D) 8 and 8

Question 6

If the loop is to be executed at least once, the condition should be checked at the__________ .

A) top of the loop
B) middle of the loop
C) bottom of the loop
D) Nothing should be checked.

Question 7

The following statement is valid.

Question 8

How many times will HI be displayed when the following lines are executed?
Dim c As Integer = 12
Do
lstBox.Items.Add("HI")
c += 3
Loop Until (c >= 30)

A) 5
B) 9
C) 6
D) 4
E) 10

Question 9

In the following code segment, what type of variable is counter?
Dim temp, counter, check As Integer
Do
temp = CInt(InputBox("Enter a number."))
counter += temp
If counter = 10 Then
check = 0
End If
Loop Until (check = 0)

A) counter
B) accumulator
C) sentinel
D) loop control variable

Question 10

In analyzing the solution to a program, you conclude that you want to construct a loop so that the loop terminates either when (a < 12) or when (b = 16). Using a Do loop, the test condition should be

A) Do While (a > 12) Or (b <> 16)
B) Do While (a >= 12) Or (b <> 16)
C) Do While (a < 12) Or (b <> 16)
D) Do While (a >= 12) And (b <> 16)
E) Do While (a < 12) And (b = 16)

Question 11

_________calculate the sums of numerical values in lists.

A) Sentinels
B) Counter variables
C) Accumulator variables
D) Nested loops

Question 12

When Visual Basic executes a Do While loop it first checks the truth value of the__________ .

A) pass
B) loop
C) condition
D) statement

Question 13

The following two sets of code produce the same output.
5 )\end{array}">$$\begin{array} { l l } \text { Dim num As Integer } = 1 & \text { Dim num As Integer } = 1 \\\text { Do While nam } < = 5 & \text { Do } \\\text { lstBox.Items.Add ("Hello") } & \text { lstBox. Items. Add ("Hello") } \\\text { num } + = 1 & \text { num } + = 1 \\\text { Loop } & \text { Loop Until (nam } > 5 )\end{array}$$

Question 14

The following are equivalent While and Until statements.
While (num > 2) And (num < 5)
Until (num <= 2) Or (num >= 5)

Question 15

What numbers will be displayed in the list box when the button is clicked? Private Sub btnDisplay_Click(...) Handles btnDisplay.Click Dim num as Double = 10 Do While num > 1 lstBox.Items.Add(num) num = num - 3 Loop End Sub

A) 10, 7, and 4
B) 10, 7, 4, and 1
C) 10, 7, 4, 1, and -2
D) No output

Question 16

A Do While loop checks the While condition before executing the statements in the loop.

Question 17

If the While condition in a Do While loop is false the first time it is encountered, the statements in the loop are still executed once.

Question 18

Which While statement is equivalent to Until num < 100?

A) While num <= 100
B) While num > 100
C) While num >= 100
D) There is no equivalent While statement.

Question 19

What is wrong with the following Do loop? Dim index As Integer = 1 Do While index <> 10 lstBox.Items.Add("Hello") index += 2 Loop

A) It should have been written as a Do Until loop.
B) It is an infinite loop.
C) The test variable should not be changed within the loop itself.
D) Nothing

Question 20

What is wrong with the following Do loop? Dim index As Integer = 1 Do While index <> 9 lstBox.Items.Add("Hello") index += 1 Loop

A) The test variable should not be changed inside a Do loop.
B) The test condition will never be true.
C) This is an infinite loop.
D) Nothing

Question 21

Which of the following are valid for an initial or terminating value of a Fir...Next loop?

A) a numeric literal
B) info.Length, where info is a string variable
C) a numeric expression
D) All of the above

Question 22

In a For statement of the form shown below, what is the default step value when the "Step c" clause is omitted?
For i As Integer = a To b Step c

A) the same as a
B) the same as b
C) 0
D) 1

Question 23

A For...Next loop with a positive step value continues to execute until what condition is met?

A) The counter variable is greater than the terminating value.
B) The counter variable is equal to or greater than the terminating value.
C) The counter variable is less than the terminating value.
D) The counter variable is less than or equal to the terminating value.

Question 24

$$\text { Which of the following program segments will sum the eight numbers input by the user? }$$

A)For k As Integer = 1 To 8
s = CDbl(InputBox("Enter a number.")
S += k
Next
B) For k As Integer = 1 To 8
a = CDbl(InputBox("Enter a number.")
S += 1
Next
C) For k As Integer = 1 To 8
a = CDbl(InputBox("Enter a number.")
A += s
Next
D) For k As Integer = 1 To 8
a = CDbl(InputBox("Enter a number.")
S += a
Next

Question 25

What does the following program do with a person's name?
Private Sub btnDisplay click(...) Handles btnDisplay.click
Dim name, test As String
Dim n As String = ""
name = InputBox ("Enter your first name:")
For i As Integer $= 0$ To (name. Length - 1) Step 2
test $=$ name. Substring $( i , 1 )$
$\mathrm { n } =$ test $\& \mathrm { n }$
Next
txtBox. Text $= n$
End Sab

A) in reverse order.
B) in reverse order and skips every other letter.
C) as it was entered.
D) as it was entered, but skips every other letter.

Question 26

What is one drawback in using non-integer Step sizes?

A) Round-off errors may cause unpredictable results.
B) Decimal Step sizes are invalid in Visual Basic.
C) A decimal Step size is never needed.
D) Decimal Step sizes usually produce infinite loops.

Question 27

How many lines of output are produced by the following program segment?
For i As Integer = 1 To 3
For j As Integer = 1 To 3
For k As Integer = i to j
lstBox.Items.Add("Programming is fun.")
Next
Next
Next

A) 8
B) 9
C) 10
D) 11

Question 28

When the odd numbers are added successively, any finite sum will be a perfect square (e.g., 1 + 3 + 5 = 9 and 9 = 3^2). What change must be made in the following program to correctly demonstrate this fact for the first few odd numbers? Private Sab btnDisplay_Click $( \ldots )$ Handles btnDisplay.Click
Dim oddNumber As Integer
Dim sum As Integer $= 0$
For i As Integer $= 1$ To 9 Step 2 $\quad$ 'Generate first few odd numbers
oddNumber $= \mathrm { i }$
For $\mathrm { j }$ As Integer $= 1$ To oddNumber Step 2 $\quad$ 'Add odd numbers
sum $+ = j$
Next
lstBox.Iteins.Add (sum & " is a perfect square.")
Next
End Sub

A) Change the Step size to 1 in the first For statement.
B) Move oddNumber = i inside the second For loop.
C) Reset sum to zero immediately before the second Next statement.
D) Reset sum to zero immediately before the first Next statement.

Question 29

Assuming the following statement, what is the For...Next loop's counter variable?
For yr As Integer = 1 To 5

A) 1
B) 5
C) To
D) yr

Question 30

A Do…Loop Until block is always executed at least once.

Question 31

Which of the following loops will always be executed at least once when it is encountered?

A) a For...Next loop
B) a Do loop having posttest form
C) a Do loop having pretest form
D) none of the above.

Question 32

How many times will PETE be displayed when the following lines are executed?
For c As Integer = 15 to -4 Step -6
lstBox.Items.Add("PETE")
Next

A) 1
B) 2
C) 3
D) 4

Question 33

Suppose the days of the year are numbered from 1 to 365 and January 1 falls on a Tuesday as it did in 2013. What is the correct For statement to use if you want only the numbers for the Fridays in 2013?

A) For i As Integer = 3 to 365 Step 7
B) For i As Integer = 1 to 365 Step 3
C) For i As Integer = 365 To 1 Step -7
D) For i As Integer = 3 To 365 Step 6

Question 34

What will be displayed by the following program when the button is clicked? Private Sub btnDisplay_Click(...) Handles btnDisplay.Click
Dim a As String, n, c As Integer
a = "HIGHBACK"
n = CInt(Int)
c = 0
For k As Integer = 0 To n - 1
If a.Substring(k, 1) > a.Substring(7 - k, 1) Then
c += 1
End If
Next
txtBox.Text = CStr(c)
End Sub

A) 1
B) 2
C) 3
D) 4
E) 5

Question 35

What will be displayed by the following program when the button is clicked?
Private Sub btnDisplay_Click(...) Handles btnDisplay.Click
Dim s As Double
s = 0
For k As Integer = 1 To 5
If k / 2 = Int(k / 2) Then
s += k
End If
Next
txtBox.Text = CStr(s)
End Sub

A) 12
B) 9
C) 15
D) 6

Question 36

Which loop computes the sum of 1/2 + 2/3 + 3/4 + 4/5 + … + 99/100?

A) For n As Integer = 1 To 99
s += n / (1 + n)
Next
B) For q As Integer = 100 To 1
s += (q + 1) /q
Next
C) For d As Integer = 2 To 99
s = 1 / d + d / (d + 1)
Next
D) For x As Integer = 1 To 100
s += 1 / (x + 1)
Next

Question 37

What is the value of j after the end of the following code segment?
For j As Integer = 1 to 23
lstBox.Items.Add("The counter value is " & j)
Next

A) 22
B) 23
C) 24
D) j no longer exists

Question 38

A counter variable is normally incremented or decremented by 1.

Question 39

What will be displayed when the following lines are executed?
txtBox.Clear
For k As Integer = 1 To 3
txtBox.Text &= "ABCD".Substring(4 - k, 1)
Next

A) ABC
B) CBA
C) DBA
D) DCBA
E) DCB

Question 40

When the number of repetitions needed for a set of instructions is known before they are executed in a program, the best repetition structure to use is a(n)

A) Do While...Loop structure.
B) Do...Loop Until structure.
C) For...Next loop.
D) If blocks.

Question 41

If the counter variable of a For...Next loop will assume values that are not whole numbers, then the variable should not be of type Integer.

Question 42

The following lines of code display all the items of lstBox.
For n As Integer = 1 to lstBox.Items.Count lstBox2.Items.Add(lstBox.Items(n))
Next

Question 43

If one For...Next loop begins inside another For...Next loop, it must also end within this loop.

Question 44

The body of a For...Next loop in Visual Basic will always be executed once no matter what the initial and terminating values are.

Question 45

The step value of a For...Next loop can be given by a numeric literal, variable, or expression.

Question 46

The value of the counter variable in a For...Next loop need not be a whole number.

Question 47

What is the data type of the variable num if Option Infer is set to On and the statement Dim num = 7.0 is executed?

A) Integer
B) Boolean
C) Double
D) String

Question 48

When Option Infer is set to On, a statement of the form Dim num = 7 is valid.

Question 49

Which of the following expressions refers to the contents of the first row of the list box?

A) lstBox.Items(0)
B) lstBox.Items(1)
C) lstBox.Items.First
D) lstBox.Items(First)

Question 50

If the terminating value of a For...Next loop is less than the initial value, then the body of the loop is never executed.

Question 51

Which of the following expressions refers to the contents of the last row of the list box?
(A)lstBox.Items(lstBox.Items.Count)
B) lstBox.Items(lstBox.Items.Count - 1)
C) lstBox.Items(Count)
(D)lstBox.Items.Count

Question 52

One must always have a Next statement paired with a For statement.

Question 53

In a For...Next loop, the initial value should be greater than the terminating value if a negative step is used and the body of the loop is to be executed at least once.

Question 54

The variable index declared with the statement For index As Integer = 0 To 5 cannot be referred to outside of the For…Next loop.

Question 55

Each item in a list box is identified by an index number; the first item in the list is assigned which of the following values as an index?

A) a randomly assigned value
B) 1.
C) a value initially designated by the programmer
D) 0

Question 56

When one For...Next loop is contained within another, the name of the counter variable for each For...Next loop may be the same.

Question 57

The following code segment is valid.
If (firstLetter > "A") Then
For x As Integer = 1 to 100
lstBox.Items.Add(x)
Next
End If

Question 58

The value of the counter variable should not be altered within the body of a For…Next loop.

Question 59

If the initial value is greater than the terminating value in a For...Next loop, the statements within are still executed one time.

Question 60

A For...Next loop cannot be nested inside a Do loop.

Question 61

If a list box contains all numbers, then which of the following values can be calculated without using a loop?

A) average value of the numbers
B) largest number
C) smallest number
D) number of numbers

Question 62

If no item in a list box is selected, the value of lstBox.SelectedIndex is 0.

Question 63

Which of the following is not a main type of event that can be raised by user selections of items in a list box?

A) Click event
B) SelectedIndexChanged event
C) FillDown event
D) DoubleClick event

Question 64

A list box named lstBox has its Sorted property set to True and contains the three items Cat, Dog, and Gnu in its Items collection. If the word Elephant is added to the Items collection at run time, what will be its index value?

A) 2
B) 1
C) 3
D) 0

Question 65

If a program contains procedures for both the Click and DoubleClick events on a list box and the user double-clicks on the list box, only the Click event will be raised.

Question 66

A list box named lstBox has its Sorted property set to False and contains the three items Cat, Dog, and Gnu in its list. If the word Elephant is added to the list at run time, what will be its index value?

A) 2
B) 1
C) 3
D) 0

Question 67

The value of lstBox.Items(n) is the nth item in the list box.

Question 68

The ___________data type is most suited to a flag.

A) Boolean
B) Integer
C) String
D) Double

Question 69

If a list box has its sorted property set to True and the list box contains all numbers, then the values in the list box will always be in increasing numerical order.

Question 70

Which of the statements will unhighlight any highlighted item in lstBox?

A) lstBox.SelectedItem = Nothing
B) lstBox.SelectedItem = ""
C) lstBox.SelectedIndex = 0
D) lstBox.SelectedIndex = -1

Question 71

The sorted property can only be set to True at design time.

Question 72

The number of items in ListBox1 is ListBox1.Items.Count.

Question 73

A variable that keeps track of whether a certain situation has occurred is called___________

A) a counter.
B) an accumulator.
C) a switch.
D) a flag.