Java: Add two binary numbers

Last update on May 12 2025 13:19:59 (UTC/GMT +8 hours)

Binary Addition

Write a Java program to add two binary numbers.

In digital electronics and mathematics, a binary number is a number expressed in the base-2 numeral system or binary numeral system. This system uses only two symbols: typically 1 (one) and 0 (zero).

Test Data:
Input first binary number: 100010
Input second binary number: 110010

Pictorial Presentation:

Java: Add two binary numbers

Sample Solution:

Java Code:

import java.util.Scanner;

public class Exercise17 {
 public static void main(String[] args) {
  // Declare variables to store two binary numbers, an index, and a remainder
  long binary1, binary2;
  int i = 0, remainder = 0;
  
  // Create an array to store the sum of binary digits
  int[] sum = new int[20];
  
  // Create a Scanner object to read input from the user
  Scanner in = new Scanner(System.in);

  // Prompt the user to input the first binary number
  System.out.print("Input first binary number: ");
  binary1 = in.nextLong();
  
  // Prompt the user to input the second binary number
  System.out.print("Input second binary number: ");
  binary2 = in.nextLong();

  // Perform binary addition while there are digits in the binary numbers
  while (binary1 != 0 || binary2 != 0) 
  {
   // Calculate the sum of binary digits and update the remainder
   sum[i++] = (int)((binary1 % 10 + binary2 % 10 + remainder) % 2);
   remainder = (int)((binary1 % 10 + binary2 % 10 + remainder) / 2);
   binary1 = binary1 / 10;
   binary2 = binary2 / 10;
  }
  
  // If there is a remaining carry, add it to the sum
  if (remainder != 0) {
   sum[i++] = remainder;
  }
  
  // Decrement the index to prepare for printing
  --i;
  
  // Display the sum of the two binary numbers
  System.out.print("Sum of two binary numbers: ");
  while (i >= 0) {
   System.out.print(sum[i--]);
  }
  
  System.out.print("\n");  
 }
}

Explanation:

In the exercise above -

Initialize variables to store the two binary numbers ('binary1' and 'binary2'), an array 'sum' to store the sum, and other necessary variables.
Takes two binary numbers from the user using the "Scanner" class.
Next it enters a loop to perform binary addition from the least significant digit (rightmost) to the most significant digit (leftmost).

Calculate the sum of the corresponding digits from both binary numbers and any remainder from the previous addition.
Store the least significant digit of the sum in the 'sum' array.
Update the remainder and divide both input binary numbers by 10 to move to the next digit.

After the loop, if there's still a remainder left, it adds it to the 'sum' array.
Prints the sum of the two binary numbers by iterating through the 'sum' array from the most significant digit to the least significant digit.
The result is displayed as a binary number.

Sample Output:

Input first binary number: 100010                                                                             
Input second binary number: 110010                                                                            
Sum of two binary numbers: 1010100

Flowchart:

Flowchart: Java exercises: Add two binary numbers

For more Practice: Solve these Related Problems:

Write a program to add three binary numbers instead of two.
Perform binary addition without converting to decimal.
Write a program that adds two binary numbers of different lengths.
Modify the program to add hexadecimal numbers instead of binary.

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