- October 18, 2015
- 11 Comments
- By SSDN Technologies

As we all know that float and double are data type

**Float**

It takes 4 bytes in java. It can store only 6 digit after the decimal point.

**Double **

By default any decimal values treated as double value. It takes 8 bytes of memory and it can store 15 values after point.

**If I declare the variable as – float f=10.22;**

It means I am assigning double value to float which is not possible directly. We have to write ‘f’ after 10.22 like f=10.22f. Because by default any value treated as double.

**So, during comparison what happens, let’s discuss-**

If I takes a variable as-

float num=10.3f ; // now 10.3 is float value // If I compare it with double value

if (num==10.3)

{

System.out.println (“true”)

}

Else

{

System.out.println (“false”);

} **
Output will Be :**false

Again I am comparing the values

float num=10.25f ; ** // now 10.3 is float value** **// if I compare it with double value**

if(num==10.25)** // comparing with double**

{

System.out.println(“true”);

}

else

{

System.out.println(“false”);

} **
Output will be :**– True

**Why the output is varying
**

When 10.3 is converted to binary format. This is written as 1010.010011 After the decimal values we convert it as follows:

.3*2=0.6——-> 0

0.6*2=1.2——->1

0.2*2=0.4——->0

0.4*2=0.8——->0

0.8*2=1.6——->1

0.6*2= 1.2——->1…….

Here as 6 appeared this procedure will again repeat for the n times.

**In float it takes only 6 digits after decimal value & In case of double it takes 15 digits after decimal value.**

So, the difference occurs during the comparison. And the result becomes “false”.

**If I takes 2nd scenario of 10.25f and convert it to binary:-**

10.25=1010.01

After the decimal value ,we convert it as:

.25*2=0.50——->0

0.50*2=1.00——>1…..

Now as 0 has appeared , convert it to to binary.

In case of float it will store 2 digits easily after decimal value.

In case of double it will also stores 2 digits after decimal value because 10.25 has only 2 digits after decimal value.

**So, during comparison both are same and results become “true”**

Next Topic discussion will be on decimal “.” (Decimal Dot).

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