C++ Exercises: Add two binary numbers

Last update on August 11 2025 12:58:09 (UTC/GMT +8 hours)

Binary Number Addition

Write a C++ program to add two binary numbers.

Visual Presentation:

Sample Solution:

C++ Code :

#include <iostream> // Including input-output stream header file
#include <math.h>   // Including math functions header file
using namespace std; // Using the standard namespace

int main() { // Start of the main function
    long bn1, bn2; // Declaration of variables to store binary numbers
    int i = 0, r = 0; // Initializing variables for iteration and remainder
    int sum[20]; // Array to store the sum of binary digits

    cout << "\n\n Addition of two binary numbers:\n"; // Displaying the purpose of the program
    cout << "-----------------------------------\n";
    cout << " Input the 1st binary number: ";
    cin >> bn1; // Taking input for the first binary number
    cout << " Input the 2nd binary number: ";
    cin >> bn2; // Taking input for the second binary number

    // Loop to add binary digits
    while (bn1 != 0 || bn2 != 0) {
        // Adding binary digits and remainder, storing the sum
        sum[i++] = (int)((bn1 % 10 + bn2 % 10 + r) % 2);
        r = (int)((bn1 % 10 + bn2 % 10 + r) / 2);
        bn1 = bn1 / 10; // Moving to the next digit in the first binary number
        bn2 = bn2 / 10; // Moving to the next digit in the second binary number
    }

    if (r != 0) { // Checking if there's a remaining carry
        sum[i++] = r; // Adding the remaining carry to the sum
    }

    --i; // Decrementing the index to reach the end of the sum array

    cout << " The sum of two binary numbers is: ";
    while (i >= 0) { // Loop to print the sum of binary numbers
        cout << (sum[i--]); // Printing each digit of the sum
    }
    cout << ("\n");  
    return 0; // Returning 0 to indicate successful program execution
}

Sample Output:

 Addition of two binay numbers:                                        
-----------------------------------                                    
 Input the 1st binary number: 1010                                     
 Input the 2nd binary number: 0011                                     
 The sum of two binary numbers is: 1101

Flowchart:

For more Practice: Solve these Related Problems:

Write a C++ program to add two binary numbers represented as strings and output the result as a binary string.
Write a C++ program that performs binary addition using bitwise operators and simulates the carry propagation manually.
Write a C++ program to add binary numbers by converting them to integers, summing them, and converting the result back to binary.
Write a C++ program to add two binary numbers using a loop to process each bit and output the final binary sum.

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