Adding binary numbers

Question

Does anyone know how to add 2 binary numbers, entered as binary, in Java?

For example, 1010 + 10 = 1100.

Answer 1

Try this, tested with binary and decimal and its self explanatory

public String add(String s1, String s2, int radix){
        int s1Length = s1.length();
        int s2Length = s2.length();
        int reminder = 0;
        int carry = 0;
        StringBuilder result = new StringBuilder();
        int i = s1Length -1;
        int j = s2Length -1;
        while (i >=0 && j>=0) {
            int operand1 = Integer.valueOf(s1.charAt(i)+"");
            int operand2 = Integer.valueOf(s2.charAt(j)+"");
            reminder = (operand1+operand2+carry) % radix;
            carry = (operand1+operand2+carry) / radix;
            result.append(reminder);
            i--;j--;
        }
        while(i>=0){
            int operand1 = Integer.valueOf(s1.charAt(i)+"");
            reminder = (operand1+carry) % radix;
            carry = (operand1+carry) / radix;
            result.append(reminder);
            i--;
        }
        while(j>=0){
            int operand1 = Integer.valueOf(s2.charAt(j)+"");
            reminder = (operand1+carry) % radix;
            carry = (operand1+carry) / radix;
            result.append(reminder);
            j--;
        }
        return result.reverse().toString();
    }
}

Answer 2

public String addBinary(String a, String b) { 
    int carry = 0;
    StringBuilder sb = new StringBuilder();
    for(int i = a.length() - 1, j = b.length() - 1;i >= 0 || j >= 0;i--,j--){
        int sum = carry + (i >= 0 ? a.charAt(i) - '0':0) + (j >= 0 ? b.charAt(j) - '0' : 0);
        sb.append(sum%2);
        carry =sum / 2;
    }
    if(carry > 0) sb.append(carry);
    sb.reverse();
    return sb.toString();
}

Answer 3

To dive into fundamentals:

public static String binaryAddition(String s1, String s2) {
    if (s1 == null || s2 == null) return "";
    int first = s1.length() - 1;
    int second = s2.length() - 1;
    StringBuilder sb = new StringBuilder();
    int carry = 0;
    while (first >= 0 || second >= 0) {
        int sum = carry;
        if (first >= 0) {
            sum += s1.charAt(first) - '0';
            first--;
        }
        if (second >= 0) {
            sum += s2.charAt(second) - '0';
            second--;
        }
        carry = sum >> 1;
        sum = sum & 1;
        sb.append(sum == 0 ? '0' : '1');
    }
    if (carry > 0)
        sb.append('1');

    sb.reverse();
    return String.valueOf(sb);
}

Answer 4

Java solution

static String addBinary(String a, String b) {

    int lenA = a.length();
    int lenB = b.length();
    int i = 0;

    StringBuilder sb = new StringBuilder();
    int rem = Math.abs(lenA-lenB);
    while(rem >0){
        sb.append('0');
        rem--;
    }
    if(lenA > lenB){
        sb.append(b);  
        b = sb.toString();
    }else{
        sb.append(a);
        a = sb.toString();
    }

    sb = new StringBuilder();
    char carry = '0';
    i = a.length();
    while(i > 0){
        if(a.charAt(i-1) == b.charAt(i-1)){
            sb.append(carry);
            if(a.charAt(i-1) == '1'){
                carry = '1';
            }else{
                carry = '0';
            }
        }else{
            if(carry == '1'){
                sb.append('0');
                carry = '1';
            }else{
                carry = '0';
                sb.append('1');
            }
        }
        i--;
    }

    if(carry == '1'){
        sb.append(carry);
    }

    sb.reverse();
    return sb.toString();

}

Answer 5

public class BinaryArithmetic {

    /*-------------------------- add ------------------------------------------------------------*/
    static String add(double a, double b) {
        System.out.println(a + "first val :" + b);
        int a1 = (int) a;
        int b1 = (int) b;
        String s1 = Integer.toString(a1);
        String s2 = Integer.toString(b1);
        int number0 = Integer.parseInt(s1, 2);
        int number1 = Integer.parseInt(s2, 2);

        int sum = number0 + number1;
        String s3 = Integer.toBinaryString(sum);

        return s3;
    }
    /*-------------------------------multiply-------------------------------------------------------*/

    static String multiply(double a, double b) {
        System.out.println(a + "first val :" + b);
        int a1 = (int) a;
        int b1 = (int) b;
        String s1 = Integer.toString(a1);
        String s2 = Integer.toString(b1);
        int number0 = Integer.parseInt(s1, 2);
        int number1 = Integer.parseInt(s2, 2);

        int sum = number0 * number1;
        String s3 = Integer.toBinaryString(sum);

        return s3;
    }
    /*----------------------------------------substraction----------------------------------------------*/

    static String sub(double a, double b) {
        System.out.println(a + "first val :" + b);
        int a1 = (int) a;
        int b1 = (int) b;
        String s1 = Integer.toString(a1);
        String s2 = Integer.toString(b1);
        int number0 = Integer.parseInt(s1, 2);
        int number1 = Integer.parseInt(s2, 2);

        int sum = number0 - number1;
        String s3 = Integer.toBinaryString(sum);

        return s3;
    }

    /*--------------------------------------division------------------------------------------------*/
    static String div(double a, double b) {
        System.out.println(a + "first val :" + b);
        int a1 = (int) a;
        int b1 = (int) b;
        String s1 = Integer.toString(a1);
        String s2 = Integer.toString(b1);
        int number0 = Integer.parseInt(s1, 2);
        int number1 = Integer.parseInt(s2, 2);

        int sum = number0 / number1;
        String s3 = Integer.toBinaryString(sum);

        return s3;
    }
}

Answer 6

import java.util.*;
public class BitAddition {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner sc = new Scanner(System.in);
        int len = sc.nextInt();
        int[] arr1 = new int[len];
        int[] arr2 = new int[len];
        int[] sum = new int[len+1];
        Arrays.fill(sum, 0);
        for(int i=0;i<len;i++){
            arr1[i] =sc.nextInt();
        }
        for(int i=0;i<len;i++){
            arr2[i] =sc.nextInt();
        }
        for(int i=len-1;i>=0;i--){
            if(sum[i+1] == 0){
                if(arr1[i]!=arr2[i]){
                    sum[i+1] = 1;
                }
                else if(arr1[i] ==1 && arr2[i] == 1){
                    sum[i+1] =0 ;
                    sum[i] = 1;
                }
            }
            else{
                if((arr1[i]!=arr2[i])){
                    sum[i+1] = 0;
                    sum[i] = 1;
                }
                else if(arr1[i] == 1){
                    sum[i+1] = 1;
                    sum[i] = 1;
                }
            }
        }
        for(int i=0;i<=len;i++){

        System.out.print(sum[i]);
        }
    }

}