Can someone help me with this code?

Question

This code prints "2 4 16 256 65536" and then just a bunch of 0. And I dunno why. Can someone tell me the reason?
https://code.sololearn.com/cDy6Yy8Tiyok/?ref=app

Answer 1

What you've observed is known as integer overflow. It happens when the no of bits required to represent the number exceeds its memory space.

Let's say we have a 2-bit number, so:

0 0
0 1
1 0
1 1

The number after 11 would be 00 (the leading 1 overflows) since we can't have 100 as it requires 3-bit. Integer is 32-bit by default and I hope you get the idea. 😉

Answer 2

I believe it's because Java's integer value limit, which is the 32 bit integer limit, 2,147,483,647. 65536 squared is 2 ** 32, which is higher than 2,147,483,647. :D

Answer 3

There is a very painful work around but it is not suitable for more than one value at a time. Google unsigned integer in java. Java hurt my feelings with that one.

Answer 4

quoting Andrew G
Change, "int" to "long" and it shows then next answer but the rest are all 0's, then I tested changing "int" to "double" and it worked but it gave me decimal form so, 4,294,967,296 was shown as 4.294967296
end quote

Try bigDecimal.

Answer 5

Try this:

import java.math.BigInteger;

public class Program {
public static void main(String[] args) {
for(BigInteger x = BigInteger.valueOf(2);
(x.toString()).length() < Integer.MAX_VALUE;
x = x.multiply(x)) {
System.out.println(x.toString());
}
}
}

Code Playground may time out before Integer.MAX_VALUE is reached.

Answer 6

Thanks to everyone :D