CODEWITHSUNDEEP
javatypesfloating-pointnumbersdouble
Sagar Pudi
Sagar Pudi

Reputation: 4814

Is double is also kind of float?

I heard that double is a more precise datatype and I would like to see the result of double with the help of following program but still it is giving variable result each time similar but not exact to float.
What is the difference between float and double and when to use them in real time?
Can any body explain this scenario in simple terms and specify the reason for this type of behaviour?
Thanks in advance :)

  public class DoubleResult {
        public static void main(String[] args) {
            double number=1;
            for(int i=0;i<5;i++){
                number=number+0.1;
                System.out.println(number);
            }
        }

    }

output:

1.1
1.2000000000000002
1.3000000000000003
1.4000000000000004
1.5000000000000004

Upvotes: 0

Views: 86

Answers (2)

SMA
SMA

Reputation: 37023

A computer's floating point unit works with base 2 binary and 0.2 can't be represented precisely in binary, it is called a repeater fraction. In base-2 only numbers with denominators that are powers of 2 are terminating, which I think is only .25, .50, and .75, which is why 6.5 shows up as "same".

Imagine you had two decimal types, one with six significant digits, and one with sixteen.

What value would you use to represent pi for each of those types? In both cases you'd be trying to get as close to a number which you couldn't represent exactly - but you wouldn't end up with the same value, would you?

It's the same for float(32 bits) and double(64 bits) - both are binary floating point types, but double has more precision than float. so if you need precision then go for double.

See this for more details

Upvotes: 0

Linora
Linora

Reputation: 10978

Both float and double are floating points. float is a single-precision (32 bit) floating point whereas double is a double-precision (hence the name) (64 bit)

Name    Width in Bits   Range
double  64              1.7e–308 to 1.7e+308
float   32              3.4e–038 to 3.4e+038

you can see this answer for a more precise description of the precision issue with floating points

Upvotes: 1

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