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Chapter 3 Check Point Questions

Section 3.2
▼3.2.1
List six relational operators.
▼3.2.2
Assuming that x is 1, show the result of the following Boolean expressions: 
x > 0
x < 0
x != 0
x >= 0
x != 1
▼3.2.3
Can the following conversions involving casting be allowed? Write a test program to verify it. 
boolean b = true;
i = (int)b;

int i = 1;
boolean b = (boolean)i;
Section 3.3
▼3.3.1
Write an if statement that assigns 1 to x if y is greater than 0.
▼3.3.2
Write an if statement that increases pay by 3% if score is greater than 90.
▼3.3.3
What is wrong in the following code? 
if radius >= 0
{
  area = radius * radius * PI;
  System.out.println("The area for the circle of " +
    " radius " + radius + " is " + area);
}
Section 3.4
▼3.4.1
Write an if statement that increases pay by 3% if score is greater than 90, otherwise increases pay by 1%.
▼3.4.2
What is the output of the code in (a) and (b) if number is 30? What if number is 35? 
(a)
if (number % 2 == 0) 
  System.out.println(number + " is even.");

System.out.println(number + " is odd.");

(b)
if (number % 2 == 0) 
  System.out.println(number + " is even.");
else   
  System.out.println(number + " is odd.");
Section 3.5
▼3.5.1
Suppose x = 3 and y = 2; show the output, if any, of the following code. What is the output if x = 3 and y = 4? What is the output if x = 2 and y = 2? Draw a flowchart of the code. 
if (x > 2) {
  if (y > 2) {
    z = x + y;
    System.out.println("z is " + z);
  }
}
else
  System.out.println("x is " + x);
▼3.5.2
Suppose x = 2 and y = 3. Show the output, if any, of the following code. What is the output if x = 3 and y = 2? What is the output if x = 3 and y = 3? 
if (x > 2)
  if (y > 2) {
    int z = x + y;
    System.out.println("z is " + z);
  }
else
  System.out.println("x is " + x);
▼3.5.3
What is wrong in the following code? 
if (score >= 60.0)
  System.out.println("D");
else if (score >= 70.0)
  System.out.println("C");
else if (score >= 80.0)
  System.out.println("B");
else if (score >= 90.0)
  System.out.println("A");
else
  System.out.println("F");
Section 3.6
▼3.6.1
Which of the following statements are equivalent? Which ones are correctly indented? 
(a)
if (i > 0) if 
(j > 0) 
x = 0; else 
if (k > 0) y = 0; 
else z = 0;

(b)            
if (i > 0) {
  if (j > 0)
    x = 0;
  else if (k > 0)
    y = 0;
}
else 
  z = 0;

(c)
if (i > 0)
  if (j > 0)
    x = 0;
  else if (k > 0)
    y = 0;
  else 
    z = 0;

(d)
if (i > 0)
  if (j > 0)
    x = 0;
  else if (k > 0)
    y = 0;
else 
  z = 0;
▼3.6.2
Rewrite the following statement using a Boolean expression: 
if (count % 10 == 0)
  newLine = true;
else 
  newLine = false;
▼3.6.3
Are the following statements correct? Which one is better? 
(a)
if (age < 16) 
  System.out.println
    ("Cannot get a driver's license"); 
if (age >= 16) 
  System.out.println
    ("Can get a driver's license"); 

(b)
if (age < 16) 
  System.out.println
    ("Cannot get a driver's license"); 
else 
  System.out.println
    ("Can get a driver's license");
▼3.6.4
What is the output of the following code if number is 14, 15, or 30? 
(a)
if (number % 2 == 0) 
  System.out.println
    (number + " is even"); 
if (number % 5 == 0)
  System.out.println
    (number + " is multiple of 5"); 

(b)
if (number % 2 == 0) 
  System.out.println
    (number + " is even"); 
else if (number % 5 == 0)
  System.out.println
    (number + " is multiple of 5");
Section 3.7
▼3.7.1
Which of the following is a possible output from invoking Math.random()? 
323.4, 0.5, 34, 1.0, 0.0, 0.234
▼3.7.2
a. How do you generate a random integer i such that 0 <= i < 20 ?
b. How do you generate a random integer i such that 10 <= i < 20
c. How do you generate a random integer i such that 10 <= i <= 50
d. Write an expression that returns 0 or 1 randomly.
Section 3.9
▼3.9.1
Are the following two statements equivalent? 
(a)
if (income <= 10000) 
  tax = income * 0.1; 
else if (income <= 20000) 
  tax = 1000 + 
    (income - 10000) * 0.15; 

(b)
if (income <= 10000) 
  tax = income * 0.1; 
else if (income > 10000 &&
         income <= 20000) 
  tax = 1000 + 
    (income - 10000) * 0.15;
Section 3.10
▼3.10.1
Assuming that x is 1, show the result of the following Boolean expressions. 
(true) && (3 > 4)
!(x > 0) && (x > 0)
(x > 0) || (x < 0)
(x != 0) || (x == 0)
(x >= 0) || (x < 0)
(x != 1) == !(x == 1)
▼3.10.2
(a) Write a Boolean expression that evaluates to true if a number stored in variable num is between 1 and 100.
(b) Write a Boolean expression that evaluates to true if a number stored in variable num is between 1 and 100 or the number is negative.
▼3.10.3
(a) Write a Boolean expression for |x - 5| < 4.5.
(b) Write a Boolean expression for |x - 5| > 4.5.
▼3.10.4
Assume that x and y are int type. Which of the following are legal Java expressions? 
x > y > 0
x = y && y
x /= y
x or y
x and y
(x != 0) || (x = 0)
▼3.10.5
Are the following two expressions the same? 
(a) x % 2 == 0 && x % 3 == 0 
(b) x % 6 == 0
▼3.10.6
What is the value of the expression x >= 50 && x <= 100 if x is 45, 67, or 101?
▼3.10.7
Suppose, when you run the following program, you enter the input 2 3 6 from the console. What is the output? 
public class Test {
  public static void main(String[] args) {
    java.util.Scanner input = new java.util.Scanner(System.in);
    double x = input.nextDouble();
    double y = input.nextDouble();
    double z = input.nextDouble();

    System.out.println("(x < y && y < z) is " + (x < y && y < z));
    System.out.println("(x < y || y < z) is " + (x < y || y < z));
    System.out.println("!(x < y) is " + !(x < y));
    System.out.println("(x + y < z) is " + (x + y < z));
    System.out.println("(x + y > z) is " + (x + y > z));
  }
}
▼3.10.8
Write a Boolean expression that evaluates to true if age is greater than 13 and less than 18.
▼3.10.9
Write a Boolean expression that evaluates to true if weight is greater than 50 pounds or height is greater than 60 inches.
▼3.10.10
Write a Boolean expression that evaluates to true if weight is greater than 50 pounds and height is greater than 60 inches.
▼3.10.11
Write a Boolean expression that evaluates to true if either weight is greater than 50 pounds or height is greater than 60 inches, but not both.
Section 3.11
▼3.11.1
How many days in the February of a leap year? Which of the following is a leap year? 500, 1000, 2000, 2016, and 2020?
Section 3.12
▼3.12.1
What happens if you enter an integer as 05?
Section 3.13
▼3.13.1
What data types are required for a switch variable? If the keyword break is not used after a case is processed, what is the next statement to be executed? Can you convert a switch statement to an equivalent if statement, or vice versa? What are the advantages of using a switch statement?
▼3.13.2
What is y after the following switch statement is executed? Rewrite the code using an if-else statement. 
x = 3; y = 3;
switch (x + 3) {  
  case 6:  y = 1;
  default: y += 1;
}
▼3.13.3
What is x after the following if-else statement is executed? Use a switch statement to rewrite it and draw the flowchart for the new switch statement. 
int x = 1, a = 3;
if (a == 1)
  x += 5;
else if (a == 2)
  x += 10;
else if (a == 3)
  x += 16;
else if (a == 4)
  x += 34;
▼3.13.4
Write a switch statement that displays Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, if day is 0, 1, 2, 3, 4, 5, 6, accordingly.
▼3.13.5
Rewrite the switch statement in Listing 3.8 using an if-else statement.
Section 3.14
▼3.14.1
Suppose that, when you run the following program, you enter the input 2 3 6 from the console. What is the output? 
public class Test {
  public static void main(String[] args) {
    java.util.Scanner input = new java.util.Scanner(System.in);
    double x = input.nextDouble();
    double y = input.nextDouble();
    double z = input.nextDouble();

    System.out.println((x < y && y < z) ? 
      "sorted" : "not sorted");
  }
}
▼3.14.2
Rewrite the following if statements using the conditional operator. 
if (ages >= 16)
  ticketPrice = 20;
else 
  ticketPrice = 10;
▼3.14.3
Rewrite the following conditional expressions using if-else statements.
a. score = (x > 10) ? 3 * scale : 4 * scale;
b. tax = (income > 10000) ? income * 0.2 : income * 0.17 + 1000;
c. System.out.println((number % 3 == 0) ? i : j);
▼3.14.4
Write conditional expression that returns -1 or 1 randomly.
Section 3.15
▼3.15.1
List the precedence order of the Boolean operators. Evaluate the following expressions: 
true || true && false
true && true || false
▼3.15.2
True or false? All the binary operators except = are left associative.
▼3.15.3
Evaluate the following expressions: 
2 * 2 - 3 > 2 && 4 - 2 > 5
2 * 2 - 3 > 2 || 4 - 2 > 5
▼3.15.4
Is x > 0 && x < 10 the same as x > 0 && x < 10?
Is x > 0 || x < 10 the same as x > 0 || x < 10?
Is (x > 0 || x < 10) && y < 0 the same as (x > 0 || (x < 10 && y < 0))?