CODEWITHSUNDEEP
javastringmethods
F. Ryan
F. Ryan

Reputation: 25

Java: Adding and Subtracting Digits Taken from a String

So the purpose of this program is to get the user to enter an integer that the program will recognize as a string. Then the program has to be able to recognize each of the numbers entered and manipulate them as follows. Digits are to be added together if the digits are the same or if the next digit is greater. Digits are to be subtracted if the next digit is smaller.

An example: The input "234224" should output 13(2+3+4-2+2+4)

However my program gives an output of 17. I don't know how to fix the problem. My problem is in my first if statement. When the second occurrence of "2" is read I want the program to subtract 2 from the output being calculated but instead it adds 2 because of how I coded the first if statement.

Could someone give me a solution using the same method I used if possible?

public class StringManipulation {

    public static void main(String[] args) {
        String userInt;
        int total = 0;

        Scanner input = new Scanner(System.in);

        System.out.println("Enter an integer:  ");
        userInt = input.nextLine();

        for (int k = 0; k < userInt.length(); k++) {
            int presentNum = userInt.charAt(k);
            System.out.println(userInt.charAt(k));

            if (presentNum == userInt.charAt(0)) {
                presentNum = Character.getNumericValue(presentNum);
                total += presentNum;
                System.out.println("counter currently at (same)" + total);
            } else if (presentNum >= userInt.charAt(k - 1)) {
                total += Character.getNumericValue(presentNum);
                System.out.println("counter currently at (adding)" + total);
            } else if (presentNum < userInt.charAt(k - 1)) {
                total -= Character.getNumericValue(presentNum);
                System.out.println("counter currently at (subtracting)" + total);
            }
        }

        System.out.println("Output= " + total);

        input.close();

    }
}

Upvotes: 0

Views: 683

Answers (3)

SenKumar
SenKumar

Reputation: 1

Try to change the first if condition, as follows

if (k==0) {
    presentNum = Character.getNumericValue(presentNum);
    total += presentNum;
    System.out.println("counter currently at (same)" + total);
}

Because, at the first iteration you have only one operand and you don't have take the value at 0th index for the condition, rather than that just see whether is it the first index.

Upvotes: 0

Lucian Covaliu
Lucian Covaliu

Reputation: 16

 if (presentNum == userInt.charAt(0)) {
         presentNum=Character.getNumericValue(presentNum);
         total+=presentNum;
         System.out.println("counter currently at (same)" + total);
     }

Your problem lies here. The first digit is added to the sum regardless of the previous digit. That means the output changes from 13(2+3+4-2+2+4) to 17(2+3+4 +2 +2+4).

You should have something like

    if (k==0){
         presentNum=Character.getNumericValue(presentNum);
         total+=presentNum;
    }

for the first digit.

Upvotes: 0

Dawood ibn Kareem
Dawood ibn Kareem

Reputation: 79838

Your problem is with your initial check 

if (presentNum == userInt.charAt(0))

in other words, you do stuff if the number you're looking at is the same as the first number. In this particular case, that condition kicks in when you encounter the 2 later in the string, and you end up adding it instead of subtracting it.

You probably wanted that condition to be 

if (k == 0)

Upvotes: 1

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