/*
* C Program to Input 2 Binary Strings and Print their Binary
* Sum
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int bin_verify(char []);
void sum(char [], char [], char []);

int main()
{
    char bin1[33], bin2[33], result[33];
    int len1, len2, check;
    printf("Enter binary number 1: ");
    scanf("%s", bin1);
    printf("Enter binary number 2: ");
    scanf("%s", bin2);
    check = bin_verify(bin1);
    if (check)
        {
            printf("Invalid binary number %s.
                   ", bin1);
                   exit(0);
        }
    check = bin_verify(bin2);
    if (check)
        {
            printf("Invalid binary number %s.
                   ", bin2);
                   exit(0);
        }
    sum(bin1, bin2, result);
    printf("%s + %s = %s
           ", bin1, bin2, result);
           return 0;
}

int bin_verify(char str[])
{
    int i;
    for (i = 0; i < strlen(str); i++)
        {
            if ((str[i] - '0' != 1 ) && (str[i] - '0' != 0))
                {
                    return 1;
                }
        }
    return 0;
}

void sum(char bin1[], char bin2[], char result[])
{
    int i = strlen(bin1) - 1;
    int j = strlen(bin2) - 1;
    int carry = 0, temp, num1, num2;
    while (i > -1 && j > -1)
        {
            num1 = bin1[i] - '0';
            num2 = bin2[j] - '0';
            temp = num1 + num2 + carry;
            if (temp / 2 == 1)
                {
                    carry = 1;
                    temp %= 2;
                }
            if (i > j)
                {
                    result[i + 1] = temp + '0';
                    result[strlen(bin1) + 1] = '';
                }
            else
                {
                    result[j +1] = temp + '0';
                    result[strlen(bin2) + 1] = '';
                }
            i--;
            j--;
        }
    while (i > -1)
        {
            temp = bin1[i] + carry - '0';
            if (temp / 2 == 1)
                {
                    carry = 1;
                    temp %= 2;
                }
            result[i + 1] = temp + '0';
            i--;
        }
    while (j > -1)
        {
            temp = bin2[j] + carry - '0';
            if (temp / 2 == 1)
                {
                    carry = 1;
                    temp %= 2;
                }
            result[j + 1] = temp + '0';
            j--;
        }
    if (carry)
        {
            result[0] = '1';
        }
    else
        {
            result[0] = '0';
        }
}



Enter binary number 1: 0110
Enter binary number 2: 1011
0110 + 1011 = 10001