Notes

#include <bits/stdc++.h>
using namespace std;
string xor1(string a, string b)
{
string result = "";
int n = b.length();
for (int i = 1; i < n; i++) {
if (a[i] == b[i])
result += "0";
else
result += "1";
}
return result;
}

string mod2div(string dividend, string divisor)
{
int pick = divisor.length();
string tmp = dividend.substr(0, pick);
int n = dividend.length();

while (pick < n) {
if (tmp[0] == '1')
tmp = xor1(divisor, tmp) + dividend[pick];
else
tmp = xor1(std::string(pick, '0'), tmp) + dividend[pick];

// Increment pick to move further
pick += 1;
}

if (tmp[0] == '1')
tmp = xor1(divisor, tmp);
else
tmp = xor1(std::string(pick, '0'), tmp);

return tmp;
}
void encodeData(string data, string generator)
{
int l_key = generator.length();

// Appends n-1 zeroes at end of data
string appended_data
= (data + std::string(l_key - 1, '0'));

string remainder = mod2div(appended_data, generator);

// Append remainder in the original data
string codeword = data + remainder;
cout << "Remainder : " << remainder << "n";
cout << "Encoded Data (Data + Remainder) :" << codeword
<< "n";
}

int main() {
// Write C++ code here
int frame_size, gener_size;
string frame;
string generator;

cout<<"Enter the frame size: ";
cin>>frame_size;
cout<<"Enter the generator size: ";
cin>>gener_size;
cout<<"Enter the frame: ";
cin>>frame;
cout<<"Enter the generator: ";
cin>>generator;

cout<<"Sender's side: "<<endl;
encodeData(frame,generator);
return 0;
}

Output:
Enter the frame size: 6
Enter the generator size: 4
Enter the frame: 100100
Enter the generator: 1101
Sender's side:
Remainder : 001
Encoded Data (Data + Remainder) :100100001