This week's book giveaways are in the Refactoring and Agile forums.
We're giving away four copies each of Re-engineering Legacy Software and Docker in Action and have the authors on-line!
See this thread and this one for details.
Win a copy of Re-engineering Legacy Software this week in the Refactoring forum
or Docker in Action in the Agile forum!
  • Post Reply
  • Bookmark Topic Watch Topic
  • New Topic

Math.round??

 
sonir shah
Ranch Hand
Posts: 435
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
public class RoundTest
{
public static void main(String args[])
{
double d = 3.5;
int i = (int) d;
i *= (int) Math.round(d);
i *= (int) Math.round(d-6);
System.out.println(i);
}
}
Options :
1)-24
2)-36
3)-48
4)-18
5) none
I tried running the program , it should -24
Can any body explain me ?>
Sonir
 
Rob Ross
Bartender
Posts: 2205
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
double d = 3.5;
int i = (int) d;
i *= (int) Math.round(d);
i *= (int) Math.round(d-6);
System.out.println(i);
First, you assign 3.5 to the variable "d". Next, the value in d is cast to an int and stored in the variable i. By casting from a double to an int, you loose the fractional part of the number; it is simply truncated. So i gets the value 3.
Next, the static function round() in the Math class is called with a double argument of value 3.5. This returns the rounded value, which will be 4. (See the JavaDoc for how round() works.) This value (4) is cast to an int, then the "times equal" operator is applied to the operands, and the value 12 is stored in i. (i previously had 3, and we multiplied this by 4).
In the same way, the next line will evaluate to
i*= -2 (d-6 rounds to -2)
Since i currently has 12, 12*-2 = -24, and this is assigned to i.
Rob
And please add those [ CODE] tags! thanks
 
Chun Wong
Greenhorn
Posts: 3
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hi, all! I am new here. How to use "Code" tag?
Thank you!
 
Jose Botella
Ranch Hand
Posts: 2120
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Just push the button that says code an place your code between the tags that appear
 
  • Post Reply
  • Bookmark Topic Watch Topic
  • New Topic