Question

I am having a problem with this code!
I am trying to run the code in java but the answer seems pretty weird.

float a=0.1F;
float b=0.2F;
if((a+b)==0.3){
System.out.println("True");
}
else{
System.out.println("False");
}

The answer is : False
But theoretically it should be return True.
The function returns True if we use values of a and b like 0.15 and 0.15 or 0.05 and 0.25.
I am confused.
I have read somewhere that languages like Java/JavaScript implements IEEE-754 number formatting! If so, then what is this formatting and what is wrong with the code? Is there anyway to change the number format?

Answer 1

The precision difference between floats (a+b) and doubles (0.3) is causing the condition to be false. You could instead use (a+b)==0.3F. i.e.

float a = 0.1F;
float b = 0.2F;
if ((a + b) == 0.3F) {  // notice the "F"
    System.out.println("True");
} else {
    System.out.println("False");
}

True

---

EDIT: In this case, even if you use doubles the condition will be false:

double a = 0.1;
double b = 0.2;
if ((a + b) == 0.3) {
    System.out.println("True");
} else {
    System.out.println("False");
}

False

Printing 0.1 + 0.2 will reveal why (the number cannot be represented perfectly):

0.30000000000000004