Java: Add two binary numbers

Last update on April 01 2025 10:54:08 (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:

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:

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.

Java Code Editor:

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