Conversions

[Ritu Kapoor]

Why on comparing, I get the output Unequal when f is supposed to get promoted to double

Code:
----------------------------------------------------------------------
float f=12.3f;
if(f==12.3){
out.println("Equal");
}
else{
out.println("Unequal");
}
----------------------------------------------------------------------
Output: Unequal.

[Alexey Korneychuk]

Do not use == with float(double) variable

public class class22 {

public static void main(String[] args) {

double f = 12.3f;
System.out.println(f);
if (f == 12.3) {
System.out.println("Equal");
} else {
System.out.println("Unequal");
}

}
}

12.300000190734863
Unequal

[Sherry Jacob]

Hi Ritu,
Well, in Java, a number declared as a float is not the same as a double. 12.3f is a float while 12.3 is a double value.

Hence the unequality !!

[Shivani Chandna]

Originally posted by Ritu Kapoor:
Why on comparing, I get the output Unequal when f is supposed to get promoted to double

Ok promotion of float to double is happening. But it is not that which is the cause of the Unequal .This is a case of - how float and double are represented . See the site

Floating Representation for detailed information.


The following example clears this:

public class NoName {
public static void main(String [] args)
{
System.out.println(2.3f + 3.99);
System.out.println(2.3 + 3.99d);
}
}

Output is :
6.289999952316284 // float added to double - approximate representation.
6.29 // double added to double is more precise


--
Shivani

[Arvind Giri]

hi ritu,
in java float are 32 bits and doubles are 64 bits.
neither of them store accutrate value, but approxmate values.
Here double stores values of more precision(more closer to actual values) than floats so there is inequality while comparing these values.

want to know in more detail?
IEEE 754

hope this helps you.