How to find the Sum of two Binary Numbers using C#?

Adding two binary numbers in C# involves performing binary arithmetic bit by bit, just like manual addition but working in base-2. The process includes handling carry operations when the sum of bits exceeds 1.

Binary addition follows simple rules: 0 + 0 = 0, 0 + 1 = 1, 1 + 0 = 1, and 1 + 1 = 10 (which means 0 with a carry of 1).

Syntax

Following is the basic approach for binary addition −

// Extract rightmost bits
bit1 = val1 % 10;
bit2 = val2 % 10;

// Calculate sum with carry
currentSum = (bit1 + bit2 + carry) % 2;
carry = (bit1 + bit2 + carry) / 2;

How Binary Addition Works

Using String-Based Binary Addition

This approach treats binary numbers as strings and performs digit-by-digit addition −

using System;

class BinaryAddition {
    public static void Main(string[] args) {
        long val1, val2, sum = 0;
        val1 = 11110;
        val2 = 11100;

        Console.WriteLine("Binary one: " + val1);
        Console.WriteLine("Binary two: " + val2);

        sum = DisplaySum(val1, val2);
        Console.WriteLine("Sum = {0}", sum);
    }

    static long DisplaySum(long val1, long val2) {
        long i = 0, carry = 0, result = 0;
        long[] sum = new long[30];

        while (val1 != 0 || val2 != 0) {
            sum[i++] = (val1 % 10 + val2 % 10 + carry) % 2;
            carry = (val1 % 10 + val2 % 10 + carry) / 2;
            val1 = val1 / 10;
            val2 = val2 / 10;
        }
        if (carry != 0)
            sum[i++] = carry;

        i = i - 1;

        while (i >= 0)
            result = result * 10 + sum[i--];
        return result;
    }
}

The output of the above code is −

Binary one: 11110
Binary two: 11100
Sum = 111010

Using Built-in Convert Methods

A more straightforward approach using C#'s built-in conversion methods −

using System;

class BinaryAdditionBuiltIn {
    public static void Main(string[] args) {
        string binary1 = "11110";
        string binary2 = "11100";

        Console.WriteLine("Binary one: " + binary1);
        Console.WriteLine("Binary two: " + binary2);

        // Convert binary to decimal, add, then convert back
        int decimal1 = Convert.ToInt32(binary1, 2);
        int decimal2 = Convert.ToInt32(binary2, 2);
        int decimalSum = decimal1 + decimal2;

        string binarySum = Convert.ToString(decimalSum, 2);
        Console.WriteLine("Sum = " + binarySum);

        // Verification
        Console.WriteLine("Decimal equivalent: {0} + {1} = {2}", 
                          decimal1, decimal2, decimalSum);
    }
}

The output of the above code is −

Binary one: 11110
Binary two: 11100
Sum = 111010
Decimal equivalent: 30 + 28 = 58

Comparison of Approaches

Conclusion

Binary addition in C# can be performed manually using bit-by-bit arithmetic with carry handling, or more simply using built-in conversion methods. The manual approach helps understand binary arithmetic, while the built-in methods provide a cleaner, more maintainable solution for practical applications.