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abs() method of Math class

Shubhada Nandarshi
Ranch Hand

Joined: Jun 10, 2005
Posts: 59
Hi friends;

We know the abs()method of Math class returns the absulute val of the num.

but if we try


class Test{

public static void main(String args[]){
System.out.println((Math.abs(Integer.MIN_VALUE)));
System.out.println((Math.abs(-2147483648)));
System.out.println((Math.abs(-4)));
}
}

gives an o/p as:

-2147483648
-2147483648
4

Why?

is it because, the no. is very big no. & abs() can't take such big no for operation?


Shubhada
Mishra Anshu
Ranch Hand

Joined: Sep 16, 2003
Posts: 224
Integer.MAX_VALUE = 2147483647
Integer.MIN_VALUE = -2147483648

I think you are expecting abs(Integer.MIN_VALUE) = 2147483648, but that can't be represented as it exceeds the Integer's range.

So,the value is -2147483648 which you may verify
by printing

System.out.println(Integer.MAX_VALUE + 1);


"Ignorance is bliss"
Timmy Marks
Ranch Hand

Joined: Dec 01, 2003
Posts: 226
Integer.MIN_VALUE is represented in binary as 10000000000000000000000000000000. Since this is a negative number, the absolute value will be -1 * the number - The twos complement is the ones complement plus one - The ones complement will be 01111111111111111111111111111111 and when we add 1 to it, we get 10000000000000000000000000000000 (which is Integer.MIN_VALUE again!), so the problem is not that abs() cannot handle such large numbers, the problem is that ints are 32 bits.
Shubhada Nandarshi
Ranch Hand

Joined: Jun 10, 2005
Posts: 59
thanks guys.
I got the ans.

bye ,
take care.

shubha.
Bert Bates
author
Sheriff

Joined: Oct 14, 2002
Posts: 8883
    
    5
hi guys -

just a reminder - if you're studying for the 1.5 exam, this topic is not on the exam! yeah!

- Bert


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