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CPSC150 EH07
CPSC150 EH07
Q1: Which of the following is a double-selection control statement?
a.do…while.
b.for.
c.if…else.
d.if.
ANS: c. if…else.
Q2: Which of the following is not a Java keyword?
a.do
b.next
c.while
d.for
ANS: b. next
Q3: What is output by the following Java code segment?
int temp;
temp = 200;
if ( temp > 90 )
System.out.println( "This porridge is too hot." );
if ( temp < 70 )
System.out.println( "This porridge is too cold." );
if ( temp == 80 )
System.out.println( "This porridge is just right!" );
a.This porridge is too hot.
b.This porridge is too cold.
c.This porridge is just right!
d.None of the above.
ANS: a. This porridge is too hot.
Q4: Which of the following is not true about the conditional operator ( ?: )?
a.The conditional operator is a ternary operator, meaning that it takes three operands.
b.The first operand is a boolean expression.
c.The second operand is the result value if the condition evaluates to false.
d.The second operand is the result value if the condition evaluates to true.
ANS: c. The second operand is the result value if the condition evaluates to false.
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Q5: What is output by the following Java code segment?
int temp;
temp = 180;
if ( temp > 90 )
{
System.out.println( "This porridge is too hot." );
// cool down
temp = temp – ( temp > 150 ? 100 : 20 );
} // end if
else
{
if ( temp < 70 )
{
System.out.println("This porridge is too cold.");
// warm up
temp = temp + (temp < 50 ? 30 : 20);
} // end if
} // end else
if ( temp == 80 )
System.out.println( "This porridge is just right!" );
a.This porridge is too hot.
b.This porridge is too cold.
This porridge is just right!
c.This porridge is just right!
d.None of the above.
ANS: d. None of the above. (The output will be
This porridge is too hot.
This porridge is just right!)
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Q6:
Drivers are concerned with the mileage their automobiles get. One driver has kept track of several tankfuls of
gasoline by recording the miles driven and gallons used for each tankful. Develop a Java application that will input
the miles driven and gallons used (both as integers) for each tankful. The program should calculate and display the
miles per gallon obtained for each tankful and print the combined miles per gallon obtained for all tankfuls up to this
point. All averaging calculations should produce floating-point results. Use class Scanner and sentinel-controlled
repetition to obtain the data from the user.
Please fill in the missing parts of the program. Make the program run and submit your running result.
ANS:
// e07_q06.java
// Program calculates average mpg
import java.util.Scanner;
public class e07_q06
{
// perform miles per gallon calculations
public static void main( String args[] )
{
Scanner input = new Scanner( System.in );
int miles; // miles for one tankful
int gallons; // gallons for one tankful
int totalMiles = 0; // total mailes for trip
int totalGallons = 0; // total gallons for trip
double milesPerGallon; // miles per gallon for tankful
double totalMilesPerGallon; // miles per gallon for trip
// prompt user for miles and obtain the input from user
System.out.print( "Enter miles (-1 to quit): " );
miles = input.nextInt();
// exit if the input is -1 otherwise, proceed with the program
while ( miles != -1 )
{
// prompt user for gallons and obtain the input from user
System.out.print( "Enter gallons: " );
gallons = input.nextInt();
// add gallons and miles for this tank to total
totalMiles += miles;
totalGallons += gallons;
//use if statement to check if gallons is 0.
// caluclate miles per gallon for the current tank
// Print out the milesPerGallon
// Missing Part A
// end of Missing Part A
//use if statement to check if totalGallons is 0.
// calculate miles per gallon for the total trip.
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// Print out the totalMilesPerGallon
// Missing Part B
// End of Missing Part B
// prompt user for new value for miles
System.out.print( "Enter miles (-1 to quit): " );
miles = input.nextInt();
} // end while loop
} // end main method
} // end class e07_q06
Q7
The following program already can print out the difference between conditional OR(||) operator and unconditional
OR (|) operators Modify the following program . Modify the program and let the program can print out the
difference between conditional AND(&&) operator and unconditional AND (&) operators. Submit your running
results.
// e07_q07.java
// Program can print out the difference between conditional OR(||) operator and unconditional OR (|) operators.
// Program can print out the difference between conditional AND(&&) operator and unconditional AND (&)
operators.
import java.util.Scanner;
public class e07_q07
{
// perform miles per gallon calculations
public static void main( String args[] )
{
Scanner input = new Scanner( System.in );
int x;
// for test operators
boolean y; // for run boolean expressions
int z;
// to control program stop or not
// prompt user for miles and obtain the input from user
System.out.print( "Enter any integer number to run the program (-1 to quit): " );
z = input.nextInt();
// exit if the input is -1 otherwise, proceed with the program
while ( z != -1 )
{
// Program can print out the difference between conditional OR(||) operator and unconditional OR (|) operators.
System.out.println( " difference between conditional OR(||)operator and unconditional OR(|)operators\n" );
System.out.println( " unconditional OR (|) operators: (1 == x) | (10 > x++)" );
x=1;
System.out.printf( "%s %d \n", " Before (1 == x) | (10 > x++), x = ", x);
y = (1 == x) | (10 > x++);
System.out.printf( "%s %d \n\n", "After (1 == x) | (10 > x++), x = ", x);
x=1;
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System.out.println( " Conditional OR (||) operators: (1 == x) || (10 > x++) " );
System.out.printf( "%s %d \n ", " Before (1 == x) | |(10 > x++), x = ", x);
y = (1 == x) || (10 > x++);
System.out.printf( "%s %d \n \n", "After (1 == x) | |(10 > x++), x = ", x);
// print out the difference between conditional AND(&&) operator and unconditional AND ($) operators.
System.out.println( "difference between conditional AND($$) operator and unconditional AND (&) operators\n" );
// Missing Part
// End of Missing Part
// prompt user for new try
System.out.print( "Enter any integer number to run the program (-1 to quit): " );
z = input.nextInt();
} // end while loop
} // end main method
} // end class e07_q07
Q8:
The US federal personal income tax is calculated based on the filing status and taxable income. There are four filing
statuses: single filers, married filing jointly, married filing separately, and head of household. The tax rates for 2002
are shown in Table 3.1
Please read the following program and fill in “left for Exercise” parts. Make you program run and submit your
running result.
// e07_q08.java: Computer Tax with Selection Statement
import javax.swing.JOptionPane;
public class e07_q08 {
public static void main(String[] args) {
// Prompt the user to enter filing status
String statusString = JOptionPane.showInputDialog(
"Enter the filing status:\n" +
"(0-single filer, 1-married jointly,\n" +
"2-married separately, 3-head of household)");
int status = Integer.parseInt(statusString);
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// Prompt the user to enter taxable income
String incomeString = JOptionPane.showInputDialog(
"Enter the taxable income:");
double income = Double.parseDouble(incomeString);
// Compute tax
double tax = 0;
if (status == 0) { // Compute tax for single filers
if (income <= 6000)
tax = income * 0.10;
else if (income <= 27950)
tax = 6000 * 0.10 + (income - 6000) * 0.15;
else if (income <= 67700)
tax = 6000 * 0.10 + (27950 - 6000) * 0.15 +
(income - 27950) * 0.27;
else if (income <= 141250)
tax = 6000 * 0.10 + (27950 - 6000) * 0.15 +
(67700 - 27950) * 0.27 + (income - 67700) * 0.30;
else if (income <= 307050)
tax = 6000 * 0.10 + (27950 - 6000) * 0.15 +
(67700 - 27950) * 0.27 + (141250 - 67700) * 0.30 +
(income - 141250) * 0.35;
else
tax = 6000 * 0.10 + (27950 - 6000) * 0.15 +
(67700 - 27950) * 0.27 + (141250 - 67700) * 0.30 +
(307050 - 141250) * 0.35 + (income - 307050) * 0.386;
}
else if (status == 1) { // Compute tax for married file jointly
// Left as exercise
}
else if (status == 2) { // Compute tax for married separately
// Left as exercise
}
else if (status == 3) { // Compute tax for head of household
// Left as exercise
}
else {
System.out.println("Error: invalid status");
System.exit(0);
}
// Display the result
JOptionPane.showMessageDialog(null, "Tax is " +
(int)(tax * 100) / 100.0);
}
}
Q9:
Using switch statements to replace if- else statements in Question 8. Make the program run and submit your
running result.
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