CODEWITHSUNDEEP
javaarraysintegeraddition
Stephen Francis
Stephen Francis

Reputation: 5

Add two Integers up to 50 digits

This is the actual question:

Write an interactive program that adds two integers of up to 50 digits each (Represents integer as an array of digits).

This is a homework question and the language to be used is Java. I got this far but I don't think it is even close.
1. It is not taking input more than 20 digits but have to work with 50 digits.
2. The method 'integerToDigits' is producing two arrays but i am unable to sort out how to use them and add them in the main method.
Help please.

package One;

import java.util.Scanner;

public class AddInt {

    public static void main(String[] args) {
        Long x,y;
        Long a[] = new Long[50];
        Long b[] = new Long[50];
        System.out.println("Please enter two numbers which have no more than 50 digits: ");
        Scanner s = new Scanner(System.in);
        x = s.nextLong();
        y = s.nextLong();
        System.out.println(x+ "and "+y);
        integerToDigits(x);
        integerToDigits(y);
    }
    public static Long[] integerToDigits(Long n){
        Long digits[] = new Long[50];
        Long temp = n;
        for(int i = 0; i < 50; i++){
            digits[49-i] = temp % 10;
            temp /= 10;
        }
        return digits;
    }
}

Upvotes: 0

Views: 4020

Answers (2)

Dan Temple
Dan Temple

Reputation: 2764

It is not taking input more than 20 digits but have to work with 50 digits.

This is because you're using x = s.nextLong() which is trying to convert the input to a long. The maximum long value is 9223372036854775807 which is nowhere near 50 digits. You'll need to get the input as a String and then covert that to your int[]

The method 'integerToDigits' is producing two arrays, but I am unable to sort out how to use them and add them in the main method.

In terms of adding up the arrays of digits, you can use the same process we learn very early on in school.

  • Add the units, then carry over any tens.
  • Add the tens and carry over any hundreds.
  • Add the hundreds and carry over any thousands.
  • ...

This process can be iterated adding each order of magnitude with the carry over from the previous one.

Hopefully those tips give you a way to solve your problem.

If you do want a solution, I've produced one here that seems to work as you require. (Although not in ideone apparently)

Upvotes: 1

Fredrik
Fredrik

Reputation: 10646

If "Represents integer as an array of digits" is a suggestion and not a requirement a solution using BigInteger would look something like:

// read numbers from input
// store first value as String "firstNumber"
// store second value as String "secondNumber"

BigInteger a = new BigInteger(firstNumber); 
BigInteger b = new BigInteger(secondNumber);
BigInteger result = a.add(b);
System.out.println("Result is " + result.toString());

If "Represents integer as an array of digits" is a requirement, well, then it's a silly assignment :) No one would store an integer like that. Worst case, I'd store it as a String if BigInteger was not allowed.

Upvotes: 1

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