Deck 4: Loops and Files

Question 1

What will be the values of x and y as a result of the following code? int x = 25, y = 8;
X += y++;

A) x = 25, y = 8
B) x = 33, y = 8
C) x = 33, y = 9
D) x = 34, y = 9

Answer 1

C

Question 2

____________ is the process of inspecting data given to the program by the user and determining if it is valid.

A) Data parsing
B) Input validation
C) User authentication
D) Defensive coding

Answer 2

B

Question 3

What will be the value of x after the following code is executed? int x = 10;
While (x < 100)
{
X += 10;
}

A) 90
B) 100
C) 110
D) This is an infinite loop

Answer 3

B

Question 4

Each repetition of a loop is known as what?

A) An iteration
B) A cycle
C) An execution
D) A Lap

Question 5

How many times will the following do-while loop be executed? int x = 11;
Do
{
X += 20;
} while (x > 100);

A) 0
B) 1
C) 4
D) 5

Question 6

This type of loop will always be executed at least once.

A) pre-test loop
B) post-test loop
C) sentinel loop
D) for loop

Question 7

What will be the value of x after the following code is executed? int x, y = 4, z = 6;
X = (y++) * (++z);

A) 24
B) 28
C) 30
D) 35

Question 8

If a loop does not contain within itself a way to terminate, it is called a(n)

A) while loop
B) do-while loop
C) for loop
D) infinite loop

Question 9

What will be the value of x after the following code is executed? int x = 10;
Do
{
X *= 20;
}
While (x > 5);

A) 10
B) 200
C) This is an infinite loop.
D) The loop will not be executed, the initial value of x > 5.

Question 10

This is a control structure that causes a statement or group of statements to repeat.

A) Block
B) Loop
C) Prefix mode
D) Body

Question 11

A loop that repeats a specific number of times is known as a(n)

A) sentinel loop
B) conditional loop
C) counter-controlled loop
D) infinite loop

Question 12

In the following code, what values could be read into number to terminate the while loop? Scanner keyboard = new Scanner(System.in);
System.out.print("Enter a number: ");
Int number = keyboard.nextInt();
While (number < 100 && number > 500)
{
System.out.print("Enter another number: ");
Number = keyboard.nextInt();
}

A) Numbers less than 100 or greater than 500
B) Numbers in the range 100 - 499
C) Numbers in the range 100 - 500
D) The boolean condition can never be true

Question 13

This type of loop allows the user to decide the number of iterations.

A) Counter-controlled loop
B) Dynamically executed loop
C) User controlled loop
D) Infinite loop

Question 14

What will be the value of x after the following code is executed? int x = 10, y = 20;
While (y < 100)
{
X += y;
}

A) 90
B) 110
C) 210
D) This is an infinite loop

Question 15

How many times will the following for loop be executed? for (int count = 10; count <= 21; count++)
System.out.println("Java is great!!!");

A) 1
B) 10
C) 12
D) 0

Question 16

This variable controls the number of times that the loop iterates.

A) Counter variable
B) Loop control variable
C) Running total
D) Decrement variable

Question 17

The increment operator is:

A) ++
B) --
C) *=
D) -=

Question 18

This is a value that signals when the end of a list of values has been reached.

A) Terminal value
B) Final value
C) End value
D) Sentinel

Question 19

If you are using a block of statements, don't forget to enclose all of the statements in a set of:

A) Braces
B) Double quotes
C) Semicolons
D) Parentheses

Question 20

What will be the value of x after the following code is executed? int x = 10;
For (int y = 5; y < 20; y +=5)
X += y;

A) 40
B) 25
C) 30
D) Invalid for statement

Question 21

Which of the following will open a file named MyFile.txt and allow you to append data to its existing contents?

A) FileWriter fwriter = new FileWriter("MyFile.txt", true);
PrintWriter outFile = new PrintWriter(fwriter);
B) FileWriter fwriter = new FileWriter("MyFile.txt");
PrintWriter outFile = new PrintWriter(fwriter);
C) PrintWriter outfile = new PrintWriter("MyFile.txt", true);
D) PrintWriter outfile = new PrintWriter(true, "MyFile.txt");

Question 22

When using the PrintWriter class, which of the following import statements would you write near the top of your program?

A) import javax.swing.*;
B) import java.io.*;
C) import PrintWriter;
D) import java.file.*;

Question 23

In the following code, what values could be read into number to terminate the while loop? Scanner keyboard = new Scanner(System.in);
System.out.print("Enter a number: ");
Int number = keyboard.nextInt();
While (number < 100 || number > 500)
{
System.out.print("Enter another number: ");
Number = keyboard.nextInt();
}

A) Numbers less than 100
B) Numbers greater than 500
C) Numbers in the range 100 - 499
D) Numbers in the range 100 - 500

Question 24

What will be the value of x after the following code is executed? int x, y = 15, z = 3;
X = (y--) / (++z);

A) 3
B) 4
C) 5
D) 6

Question 25

Before entering a loop to compute a running total, the program should first do this.

A) Read all the values into main memory
B) Set the accumulator where the total will be kept to an initial value, usually zero
C) Know exactly how many values there are to total
D) Set all variables to zero

Question 26

This type of loop is ideal in situations where the exact number of iterations is known.

A) while loop
B) do-while loop
C) for loop
D) if statement

Question 27

Which of the following are pre-test loops?

A) while, for, do-while
B) while, do-while
C) while, for
D) for, do-while

Question 28

A for loop normally performs which of these steps?

A) initializes a control variable to a starting value
B) tests the control variable by comparing it to a maximum/minimum value and terminate when the variable reaches that value
C) updates the control variable during each iteration
D) all of the above
E) None of the above

Question 29

What will be the value of x after the following code is executed? int x = 10;
While (x < 100);
{
X += 10;
}

A) 90
B) 100
C) 110
D) This is an infinite loop

Question 30

What will be the value of x after the following code is executed? int x = 10, y = 20;
While (y < 100)
{
X += y;
Y += 20;
}

A) 90
B) 110
C) 130
D) 210

Question 31

How many times will the following do-while loop be executed? int x = 11;
Do
{
X += 20;
}
While (x <= 100);

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

Question 32

Given the following statement, which statement will write "Calvin" to the file DiskFile.txt? PrintWriter diskOut = new PrintWriter("DiskFile.txt");

A) System.out.println(diskOut, "Calvin");
B) DiskFile.println("Calvin");
C) PrintWriter.println("Calvin");
D) diskOut.println("Calvin");

Question 33

A sentinel value _________ and signals that there are no more values to be entered.

A) is a different data type than the values being processed
B) is a special value that cannot be mistaken as a member of the list
C) indicates the start of a list
D) guards the list

Question 34

Assume that inputFile references a Scanner object that was used to open a file. Which of the following while loops shows the correct way to read data from the file until the end of the file is reached?

A) while (inputFile != null)
{ … }
B) while (!inputFile.EOF)
{ … }
C) while (inputFile.hasNext())
{ … }
D) while (inputFile.nextLine == " ")
{ … }

Question 35

In all but rare cases, loops must contain within themselves

A) arithmetic statements
B) if statements
C) a way to terminate
D) nested loops

Question 36

What will be the values of x and y as a result of the following code? int x = 12, y = 5;
X += y--;

A) x = 12, y = 5
B) x = 16, y = 4
C) x = 17, y = 5
D) x = 17, y = 4

Question 37

What will be the value of x after the following code is executed? int x = 10;
Do
{
X *= 20;
}
While (x < 5);

A) 10
B) 200
C) This is an infinite loop.
D) The loop will not be executed, the initial value of x > 5.

Question 38

This is a sum of numbers that accumulates with each iteration of a loop.

A) Running total
B) Final total
C) Grand finale
D) Galloping total

Question 39

What will be printed after the following code is executed? for (int number = 5; number <= 15; number +=3)
System.out.print(number + ", ");

A) 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
B) 5, 8, 11, 14, 17,
C) 5, 8, 11, 14,
D) This is an invalid for statement

Question 40

A loop that executes as long as a particular condition exists is called a(n)

A) sentinel loop
B) conditional loop
C) count-controlled loop
D) infinite loop

Question 41

Assuming that inputFile references a Scanner object that was used to open a file, which of the following statements will read an int from the file?

A) int number = inputFile.nextInt();
B) int number = inputFile.next();
C) int number = inputFile.readInt();
D) int number = inputFile.integer();

Question 42

This is an item that separates other items.

A) Controller
B) Partition
C) Doorway
D) Delimiter

Question 43

This type of loop is ideal in situations where you always want the loop to iterate at least once.

A) while loop
B) do-while loop
C) for loop
D) if statement

Question 44

Which of the following will open a file named MyFile.txt and allow you to read data from it?

A) File file = new File("MyFile.txt");
B) Scanner inputFile = new Scanner("MyFile.txt");
C) File file = new File("MyFile.txt");
Scanner inputFile = new Scanner(file);
D) PrintWriter inputFile = new PrintWriter("MyFile.txt");

Question 45

Java provides a set of simple unary operators designed just for incrementing and decrementing variables.

Question 46

When you open a file with the PrintWriter class, the class can potentially throw an IOException.

Question 47

When the continue statement is encountered in a loop, all the statements in the body of the loop that appear after it are ignored, and the loop prepares for the next iteration.

Question 48

The do-while loop must be terminated with a semicolon.

Question 49

The while loop has two important parts: (1) a boolean expression that is tested for a true or false value, and (2) a statement or block of statements that is repeated as long as the expression is true.

Question 50

A file must always be opened before using it and closed when the program is finished using it.

Question 51

The do-while loop is a pre-test loop.

Question 52

You can use the PrintWriter class to open a file for writing and write data to it.

Question 53

In the for loop, the control variable cannot be initialized to a constant value and tested against a constant value.

Question 54

When the break statement is encountered in a loop, all the statements in the body of the loop that appear after it are ignored, and the loop prepares for the next iteration.

Question 55

In a for statement, the control variable can only be incremented.

Question 56

When you pass the name of a file to the PrintWriter constructor, and the file already
exists, it will be erased and a new empty file with the same name will be created.

Question 57

You can use this method to determine whether a file exists.

A) The Scanner class's exists method
B) The File class's exists method
C) The File class's canOpen method
D) The PrintWriter class's fileExists method