如何让 c++ 中的这个二进制加法程序工作？

Question

I am trying to create a program that takes in 2 arrays in binary form and calculates the addition of said arrays, although I keep getting the error:

"munmap_chunk(): invalid pointer Aborted (core dumped) "

The code is below

#include <iostream>
#include <string>

using namespace std;

string binaryAddition(int num1[], int num2[]) {


    // BINARY 1: 111011101011
    // BINARY 2: 000000000011


    int carry = 0;
    string res = "";

    for (int i = 11; i >= 0; i--) {

        if (num1[i] == 0 && num2 == 0 && carry == 0) {
            res += "1";
        } else if (num1[i] == 0 && num2[i] == 1 && carry == 0) {
            res += "1";
        } else if (num1[i] == 1 && num2[i] == 0 && carry == 0) {
            res += "1";
        } else if (num1[i] == 1 && num2[i] == 1 && carry == 0) {
            res += "0";
            carry = 1;
        } else if (num1[i] == 0 && num2[i] == 0 && carry == 1) {
            res += "1";
            carry = 0;
        } else if (num1[i] == 0 && num2[i] == 1 && carry == 1) {
            res += "0";
            carry = 1;
        } else if (num1[i] == 1 && num2[i] == 0 && carry == 1) {
            res += "0";
            carry = 1;
        } else if (num1[i] == 1 && num2[i] == 1 && carry == 1) {
            res += "1";
            carry = 1;
        }

    }
    
    cout << res;

}

int main() {

    int num1[12] = {1,1,1,0,1,1,1,0,1,0,1,1};
    int num2[12] = {0,0,0,0,0,0,0,0,0,0,1,1};

    binaryAddition(num1, num2);
}

Would appreciate some help, Thankyou!

Answer 1

You can have to calculate the result least significant bit to most significant bit to carry the bit forward. When you print it then you want go the opposite direction:

#include <iostream>
#include <string>

using namespace std;

string binaryAddition(int num1[], int num2[]) {
    int num3[12] = {};
    int carry = 0;
    for(int i = 11; i >= 0; i--) {
        int sum = num1[i] + num2[i] + carry;
        num3[i] = sum % 2;
        carry = sum / 2;
    }

    string res = "";
    for(int i = 0; i < 12; i++) {
        res += num3[i] ? "1" : "0";
    }
    return res;
}

int main() {
    int num1[] = {1,1,1,0,1,1,1,0,1,0,1,1};
    int num2[] = {0,0,0,0,0,0,0,0,0,0,1,1};
    cout << binaryAddition(num1, num2) << "\n";
}

Answer 2

You set your binaryAddition function to be returning a string but it never returns. So, there are two ways you can do. Either return your res and then cout it in the main:

string binaryAddition(int num1[], int num2[]) {
    ...
    return res;
}
int main() {
    ...
    string res = binaryAddition(num1, num2);
    cout << res;
    ...
}

Or, you can change its return type to void :

void binaryAddition(int num1[], int num2[]) {
    ...  // keep the rest
    cout << res;
}

Well, you'll need to debug your binaryAddition function and reverse the string too.

Answer 3

I suggest to use bitsets instead. Here is a good example how it could be done https://alikhuram.wordpress.com/2013/05/15/performing-arithmetic-on-bitsets-in-c/