Deck 6: Flow of Control, Part 2: Looping

Question 1

Why is the first read called the priming read?

A) The first read is the most important one.
B) Like priming a pump, the first read feeds the condition of the while loop for the first iteration.
C) If the first read returns a true block, it is the only read needed.
D) All of these are correct.

Answer 1

B

Question 2

How many times will a loop with the for loop header for ( i = 5; i < 15; i++ ) execute?

A) 1
B) 5
C) 10
D) 11
E) 15

Answer 2

C

Question 3

How many times will a loop with the for loop header for ( i = 5; i <= 15; i++ ) execute?

A) 1
B) 5
C) 10
D) 11
E) 15

Answer 3

D

Question 4

Using the for loop header for( int i = 0; i < 5; i++ ), the variable i will still be in scope after we exit the for loop.

Question 5

A while loop can be nested inside a for loop and vice versa.

Question 6

If the while loop condition is false the first time it is evaluated, the number of iterations that will be in the body of the loop is __________.

Question 7

When you write a program that expects an input value within a certain range only, you should not forget to test the __________ case.

Question 8

The while loop is used to process each input value, one at a time, until a signal tells us that there is no more input. This is called:

A) event-controlled looping.
B) either/or looping.
C) sentinel looping.
D) loop updating.

Question 9

What is each execution of the loop body called?

A) An integer
B) An iteration
C) An endless loop
D) An infinite loop

Question 10

The while loop condition is a boolean expression.

Question 11

A sentinel value in a while loop provides a function similar to which of the following?

A) A child holding a kitten
B) A speed limit sign on an interstate
C) A divider bar on a checkout lane's conveyor belt
D) A quicksand trap in a desert

Question 12

Which of the following arguments constructs a File object with the pathname file name so that the file name is platform independent?

A) hasNext( )
B) nextDouble( )
C) next( )
D) None of these is correct.

Question 13

What is the argument list for the nextFloat( ) method in the Scanner class?

A) an int
B) a Float
C) Returns true if there is another token in the input stream; false, otherwise
D) None of these is correct.

Question 14

Without the priming read, the while loop continually processes the same data item, leading to an endless loop.

Question 15

The hasNext method in the Scanner class returns true if the input has another token, and false otherwise.

Question 16

Using an event-controlled while loop and an accumulation operation to create a calculator, a result that is higher than the correct total occurs because the total variable was not initialized to 0.

Question 17

A logic error is likely to happen if we set the sentinel value -1 in an addition calculator.

Question 18

Calculating an average is a combination of addition and counting.

Question 19

To get a floating-point average, type cast one of the variables (either total or count) to a double or a float to force the division to be performed as floating-point. double average = (double) ( total ) / count;

Question 20

It is a good idea to initialize the maximum value to 0 when trying to find maximum values.

Question 21

Some code is already coded with a for loop. It is possible to rewrite that code using a while loop.

Question 22

An InputMismatchException is generated while using Scanner. What can you conclude?

A) The user made a typo.
B) The user misunderstood and entered the wrong data.
C) The user typed "one" instead of "1."
D) Any of these are possible.

Question 23

Which of the following questions should you ask to verify a clean program?

A) Does the program produce correct results with a set of known inputs?
B) Does the program produce correct results if the sentinel value is the first and only input?
C) Does the program deal appropriately with invalid input?
D) All of these are required tests.

Question 24

In the do/while loop, the loop condition is tested at the end of the loop, instead of at the beginning, as in the while loop.

Question 25

Using an if statement to validate input will find all errors without reprompting.

Question 26

Before the loop begins, if you know the number of times the loop body should execute, you can use a:

A) for loop.
B) toggle loop.
C) do loop.
D) get next loop.

Question 27

If you want to loop between the values 3 included and 7 excluded, the for loop header would be:
for( int count = 3; count < 7; count++ )

Question 28

You have a for loop nested in a while loop in order to find prime numbers. The proper way is to set the flag to false before starting the for loop that checks for factors. Inside the for loop, set the flag to true when a factor is found. After the for loop terminates, check the value of the flag. If it is still false, no factors were found and the number is prime.

Question 29

while loops can be nested.

Question 30

for loops can be nested.

Question 31

Which Java class enables us to read data easily from a file?

A) IO
B) Scanner
C) Read
D) File

Question 32

How many times will a loop with the for loop header for ( i = 0; i <= 6; i++ ) execute?

A) 1
B) 5
C) 6
D) 7

Question 33

How many times will a loop with the for loop header for ( i = 0; i < 6; i++ ) execute?

A) 1
B) 5
C) 6
D) 7

Question 34

When you use a while loop to count how many values meet a certain condition, you should initialize the variable holding the count to:

A) 0.
B) 1.
C) NULL.
D) There is no need to initialize it.

Question 35

When you use a while loop to compute the average of several values, what variables do you need to keep track of (in addition to holding the value being processed)?

A) The sum of the values
B) How many values have been processed
C) None
D) The sum of the values and how many values have been processed

Question 36

When a loop condition is grade >= 90, what values would you use to test your loop?

A) 88 and 89
B) 0 and 90
C) 89, 90, and 91
D) 90, 91, and 92

Question 37

When you use a sentinel value for the condition of a loop that processes user inputs, what case should you not forget to test?

A) The sentinel value is the last input value.
B) The sentinel value is the first input value.
C) The sentinel value is the third input value.

Question 38

The loop condition is a boolean expression.

Question 39

When asking the user for an integer value, it is possible that the user enters a character that is not an integer; using a while loop, we can keep asking the user for an integer until the user enters one.

Question 40

The loop condition can be a complex condition involving several logical, equality, and relational operators.

Question 41

You should always put a semicolon after the closing parenthesis in a for loop header.

Question 42

In a for loop, a loop control variable is usually, but not always, for counting.

Question 43

Putting a semicolon after the loop condition of a while loop will most likely result in a(n) __________ or endless loop.

Question 44

When reading data from a user, the first time we read is called the __________.

Question 45

When you use a while loop to compute the sum of several values, you should initialize the variables holding the sum to:

A) 0.
B) 1.
C) NULL.
D) There is no need to initialize them.

Question 46

When you use a while loop to compute the product of several values, you should initialize the variables holding the product to:

A) 0.
B) 1.
C) NULL.
D) There is no need to initialize them.

Question 47

In a for loop header, statements are separated with:

A) colons.
B) commas.
C) semicolons.
D) periods.

Question 48

Assuming the for loop header for ( i = 0; i <= 7; i++ ), what will be value of i after we exit the loop?

A) 0
B) 6
C) 7
D) 8

Question 49

Assuming the for loop header for ( i = 0; i < 20; i++ ), what will be value of i after we exit the loop?

A) 0
B) 19
C) 20
D) 21

Question 50

How many times will a loop with the for loop header for ( i = 1; i <= 6; i++ ) execute?

A) 1
B) 5
C) 6
D) 7

Question 51

A special value that the user enters to signal the end of the input is called a(n) __________ value.

A) input
B) user
C) sentinel
D) looping

Question 52

When reading data from a file using a while loop, the typical condition to exit the loop is when you:

A) have read the first value in the file.
B) have read 100 values in the file.
C) have reached the end of the file.

Question 53

When we use a while loop, we always know in advance how many times the loop body will be executed.

Question 54

Curly braces around the loop body are optional if the loop body consists of only one statement.

Question 55

Curly braces around a for loop body are optional if the for loop body consists of only one statement.

Question 56

A while loop can be used for counting input values that have a certain property-for instance, positive values.

Question 57

When computing the maximum value among a number of values, we should initialize the maximum to 0.

Question 58

The body of a while loop is executed until the loop condition becomes __________.

Question 59

We typically use a for loop as a(n) __________ loop.

Question 60

Writing a String in reverse can be done using a(n) __________.

Question 61

The loop continuation condition is the ___________ of the loop termination condition.

Question 62

A loop condition may be simplified by applying __________ laws.

Question 63

Describe the conditions under which you would want to use a sentinel value.

Question 64

Evaluate this code segment, explaining any errors:
12 int count = 1;
13 int total = 1;
14 final int SENTINEL = -1;
15 int score;

Question 65

When you use a while loop to compute the average of several integer values, and assuming there is more than one such value, what do you have to worry about when dividing the sum of these values by the number of these values?

Question 66

When you use a while loop to compute the average of several values, what do you have to worry about when dividing the sum of these values by the number of these values?

Question 67

What is the output of this code sequence?
for ( int i = 5; i >= 0; i-- )
System.out.print( i + " " );
System.out.println( );