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What output is produced by the program shown in Listing 8 ?
| Listing 8 . Modulus operator with floating types. |
|---|
public class Modulus03{
public static void main(String args[]){
new Worker().doWork();}//end main()
}//end class definitionclass Worker{
public void doWork(){double myVar01 = -0.11;
double myVar02 = 0.033;System.out.println(myVar01%myVar02);
}//end doWork()}//end class definition |
Modulus operator can be used with floating types
In this case, the program returns the remainder that would be produced by dividing a double value of -0.11 by a double value of 0.033 and terminating the divide operation at the beginning of the fractional part of the quotient.
Say that again
Stated differently, the result of the modulus operation for floating types is the remainder that results after
(Did you know that division is nothing more than repetitive subtraction and multiplication is nothing more than repetitive addition?)
Modulus result is not exact
According to my hand calculator, taking into account the fact that the left operand is negative, this operation should produce a modulus result of -0.011. As you can see from the answer that follows, the result produced by the application of the modulus operation to floating types is not exact.
And the answer to the question is...
C. -0.010999999999999996
What output is produced by the program shown in Listing 9 ?
| Listing 9 . A totally incorrect modulus result. |
|---|
public class Modulus04{
public static void main(String args[]){
new Worker().doWork();}//end main()
}//end class definitionclass Worker{
public void doWork(){double myVar01 = 15.5;
double myVar02 = 1.55;System.out.println(myVar01%myVar02);
}//end doWork()}//end class definition |
A totally incorrect result
Unfortunately, due to floating arithmetic inaccuracy, the modulus operation in this program produces an entirely incorrect result. The result should be 0.0, and that is the result produced by my hand calculator.
Terminates one step too early
However, this program terminates the repetitive subtraction process one step too early and produces an incorrect remainder.
Be careful
This program is included here to emphasize the need to be very careful how you interpret the result of performing modulus operations on floating operands.
And the answer to the question is...
D. 1.5499999999999996
What output is produced by the program shown in Listing 10 ?
| Listing 10 . Not a number (NaN). |
|---|
public class Modulus05{
public static void main(String args[]){
new Worker().doWork();}//end main()
}//end class definitionclass Worker{
public void doWork(){double myVar01 = 15.5;
double myVar02 = 0.0;System.out.println(myVar01%myVar02);
}//end doWork()}//end class definition |
Floating modulus operation involves floating divide
Because the modulus operation for floating operands involves a floating divide, you might expect the result to be Infinity when the right operand value is 0.0.
Not true!
The modulus operation with floating operands and 0.0 as the right operand produces NaN , which stands for Not a Number .
What is the actual value of Not a Number ?
A symbolic constant that is accessible as Double.NaN specifies the value that is returned in this case. Be careful what you try to do with it. It has some peculiar behavior of its own.
And the correct answer is...
D. NaN
I encourage you to run the programs that I have presented in this lesson to confirm that you get the same results. Copy the code for each program into yourIDE. Then compile and run each program. Experiment with the code, making changes, and observing the results of your changes. Makecertain that you can explain why your changes behave as they do.
This section contains a variety of miscellaneous materials.
Financial : Although the Connexions site makes it possible for you to download a PDFfile for this module at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, you should be aware thatsome of the HTML elements in this module may not translate well into PDF.
I also want you to know that, I receive no financial compensation from the Connexions website even if you purchase the PDF version of the module.
In the past, unknown individuals have copied my modules from cnx.org, converted them to Kindle books, and placed them for sale on Amazon.comshowing me as the author. I neither receive compensation for those sales nor do I know who does receive compensation. If you purchase such a book, pleasebe aware that it is a copy of a module that is freely available on cnx.org and that it was made and published without my prior knowledge.
Affiliation : I am a professor of Computer Information Technology at Austin Community College in Austin, TX, and have noaffiliation with the College Board .
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