using biginteger for java program regarding virtual addresses

Question

Maybe I'm misunderstanding due to my limited use of biginteger, but I have a program that needs to take user input for page size and virtual address and calculate offset and virtual page. I can do the calculation no problem, but when comparing itegers for the input, the necessary value of virtual address ( 4294967295)is out of range. I tried to declare this number as a big int but the same operators don't seem to work. Do I have to forget the zero and just find a way to say the input is less than or equal to this number? Here is the code:

public class VAddress {

public static void main(String args[]){

    BigInteger max = new BigInteger("4294967295"); 

    Scanner PAGEinput = new Scanner(System.in);
    Scanner ADDinput = new Scanner(System.in);

      System.out.println("Please Enter the system page size (between 512 and 16384):");
    int page = PAGEinput.nextInt();

    System.out.println("Please Enter the Virtual Address: ");
    int address = ADDinput.nextInt();

    if(page >= 512 && page <= 16384){
        if( address >= 0 && address <= max){

        }
       }



     }

 }

Have you considered usage of `long`? – user3707125 Jun 05 '15 at 16:31 — user3707125, Jun 05 '15 at 16:31

score 1 · Accepted Answer · answered Jun 05 '15 at 16:30

1

BigInteger address = new BigInteger(address);
if(page >= 512 && page <= 16384){
    if(address.compareTo(new BigInteger("0"))>=0 && address.compareTo(max)<=0){

    }
}

answered Jun 05 '15 at 16:30

jst

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Though as many people will point out, long primitive type can hold the value and you can just use that instead. – jst Jun 05 '15 at 16:35
perfect, I just wanted to make sure I wasn't using too much unnecessary syntax. Thanks everybody! – guitar138 Jun 05 '15 at 16:47
`compareTo(new BigInteger("0"))` is equivalent to `signum()` – Louis Wasserman Jun 05 '15 at 17:03

score 0 · Answer 2 · edited May 23 '17 at 12:30

0

You need to turn the integer address into a BigInteger as well so that you can compare it to max, see this question

edited May 23 '17 at 12:30

Community

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answered Jun 05 '15 at 16:24

Moritz

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So something similar to this: System.out.println("Please Enter the Virtual Address: "); BigInteger address = ADDinput.nextBigInteger(); – guitar138 Jun 05 '15 at 16:28
yup. Don't forget to cast the 0 as biginteger too if you go this route – Moritz Jun 05 '15 at 16:33

using biginteger for java program regarding virtual addresses

2 Answers2