File APIs for Java Developers
Manipulate DOC, XLS, PPT, PDF and many others from your application.
The moose likes Beginning Java and the fly likes ints, floats and doubles Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login

Win a copy of REST with Spring (video course) this week in the Spring forum!
JavaRanch » Java Forums » Java » Beginning Java
Bookmark "ints, floats and doubles" Watch "ints, floats and doubles" New topic

ints, floats and doubles

Ed Lance
Ranch Hand

Joined: Aug 02, 2000
Posts: 38
Would appreciate a brief overview of these primitive data types. When coding I sometimes notice a loss of precision when moving from one to the other (especially int to float).
Fiona Barker

Joined: Jul 23, 2001
Posts: 18
Surely I can answer this without even referring to Java? A floating point number is wider and more precise than an integer. I.e., 1.0005 is not the same as 1. A "double" (64 bit floating point) is wider than a "float" (32 bit floating point) which is wider than an "int" (32 bit integer). Perhaps I'm wrong in assuming this is just a simple application of maths ...
Rob Acraman
Ranch Hand

Joined: Dec 03, 2000
Posts: 89
You may notice a loss of precision going from int-to-float when you're dealing with large numbers. With small numbers (certainly upto 1-million - probably MUCH beyond that as well, but you get my drift) the numbers should match well.
Why is this? Well, if you're really techie, read on - but beware! I'm writing this turned midnight with no reference books to hand
Consider this: Both int and float are 32 bits. Now, 32 bits can take on 2**32 distinct "values" (that is, 2-raised-to-32nd power - ie. 2 times 2 times 2 ..... 32 times). Therefore, both int and float can only have this number of distinct values as well.
The int type holds these as precise integers upto (plus-or-minus) 2**16.
The float type holds a fantastically wider range of numbers: offhand, let's say from 10**-99 through to 10**99 (positive and negative).
You can't get something for nothing. The float type has a wider range of values, but remember that it can still only hold 2**32 distinct values. That means, if there is a "good" match with integers around zero, there has to be a "worse" match with integers far from zero - ie. BIG numbers.
I agree. Here's the link:
subject: ints, floats and doubles
jQuery in Action, 3rd edition