In this post, we will learn **how to add two binary numbers in C** Programming language.

**Binary numbers** are those numbers which can be expressed in the **base-2** numeral system, a mathematical expression which uses only two symbols: ‘**0**’ and ‘**1**’.

The binary addition rules are as follows:

- 0 + 0 = 0
- 0 + 1 = 1
- 1 + 0 = 1
- 1 + 1 = 10 which is
**0**carry**1**

We will be using these rules in our program to calculate the sum of two binary numbers.

So, without further ado, let’s begin this tutorial.

**C Program To Add Two Binary Numbers**

// C Program To Add Two Binary Numbers #include <stdio.h> int main(){ long int binary1, binary2; int i = 0, rem = 0, sum[20]; // Asking for Input printf("Enter first binary number: "); scanf("%ld", &binary1); printf("Enter second binary number: "); scanf("%ld", &binary2); while (binary1 != 0 || binary2 != 0){ sum[i++] = (binary1 %10 + binary2 % 10 + rem) % 2; rem = (binary1 %10 + binary2 % 10 + rem) / 2; binary1 = binary1 / 10; binary2 = binary2 / 10; } if (rem != 0) sum[i++] = rem; --i; printf("Sum of two binary numbers is: "); while (i >= 0){ printf("%d", sum[i--]); } return 0; }

**Output**

```
Enter first binary number: 10101
Enter second binary number: 11100
Sum of two binary numbers is: 110001
```

**How Does This Program Work ?**

long int binary1, binary2; int i = 0, rem = 0, sum[20];

In this program, we have declared two long data type variables named **binary1 **and **binary2**. We have also initialized the variables** i **and **rem** to** 0**.

// Asking for Input printf("Enter first binary number: "); scanf("%ld", &binary1); printf("Enter second binary number: "); scanf("%ld", &binary2);

Then, the user is asked to enter the values of two binary numbers. These values will be stored in** binary1** and **binary2 **named variables respectively.

while (binary1 != 0 || binary2 != 0){ sum[i++] = (binary1 %10 + binary2 % 10 + rem) % 2; rem = (binary1 %10 + binary2 % 10 + rem) / 2; binary1 = binary1 / 10; binary2 = binary2 / 10; } if (rem != 0){ sum[i++] = rem; } --i; printf("Sum of two binary numbers is: "); while (i >= 0){ printf("%d", sum[i--]); }

Now, we build up a simple logic which will add the two binary numbers. The result will be printed using **printf()** function.

**Conclusion**

I hope after going through this post, you understand **how to add two binary numbers in C** Programming language.

If you have any doubts regarding the program, feel free to contact us in the comment section. We will be delighted to help you.

**Also Read:**

SagnikWhat does (–i) do in the above program ?