This week's book giveaway is in the Agile forum.
We're giving away four copies of Head First Agile and have Andrew Stellman & Jennifer Greene on-line!
See this thread for details.
Win a copy of Head First Agile this week in the Agile forum!
  • Post Reply Bookmark Topic Watch Topic
  • New Topic

Need help to understand basic arithmetics in Java  RSS feed

 
raul saini
Greenhorn
Posts: 18
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Suppose we have this expression:



now i need to know how java performs this operation.
I know the precedence but still not able to figure out.

Please explain.
Thank You
 
fred rosenberger
lowercase baba
Bartender
Posts: 12542
48
Chrome Java Linux
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
you should probably read something like this. operators all have a precedence - some get done before others, just like in math.

If i recall correctly, anything inside parens is done first, so we'd get

6*10/5*5+14/2-9+20

Then, mult/div come next, in order from left to right

60/5*5+14/2-9+20

60/5*5+14/2-9+20

12*5+14/2-9+20

60+14/2-9+20

60+7-9+20

then, addition and subtraction, in order from left to right

67-9+20
58+ 20
78



 
raul saini
Greenhorn
Posts: 18
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Thank you very much, I was performing multiple calculation at a time.
 
fred rosenberger
lowercase baba
Bartender
Posts: 12542
48
Chrome Java Linux
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
well, you can, as long as you complete ALL operations of a given precedence before any others. I could have just as easily done this:

6*10/5*5+14/2-9+(10*2);

6*10/5*5+14/2-9+20; //take care of everything inside parens

60 + 7 - 9 + 20 // take care of all multiplication and division

78 // take care of all addition and subtraction.



 
Istvan Kovacs
Ranch Hand
Posts: 100
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Note that with integer types, you can encounter issues due to losing data when performing calculations, which may make it seem that Java violates rules of arithmetics. For example:
(a / b * c) = (a * c / b) may not hold:

 
Campbell Ritchie
Marshal
Posts: 55799
164
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
That problem with integer arithmetic applies to most computer languages.
 
Rob Spoor
Sheriff
Posts: 21095
85
Chrome Eclipse IDE Java Windows
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
With floating point calculations there can even be a difference between (a+b)+c and a+(b+c).
 
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
Boost this thread!