crc.cpp

#include <iostream>
using namespace std;

string xorfun(string encoded, string crc)
{
    int crclen = crc.length();

    for (int i = 0; i <= (encoded.length() - crclen);)
    {
        for (int j = 0; j < crclen; j++)
        {
            encoded[i + j] = encoded[i + j] == crc[j] ? '0': '1';
        }
        for (; i < encoded.length() && encoded[i] != '1'; i++);

    }

    return encoded;
}

int main() {
    
    string data="";
    string crc="";
    string encoded = "";


    cout << "Enter Data bits: " << endl;
    cin >> data;

    cout << "Enter Generator: " << endl;
    cin>> crc;

    encoded += data;

    int datalen = data.length();
    int crclen = crc.length();

    for (int i = 1; i <= (crclen - 1); i++)
        encoded += '0';

    encoded = xorfun(encoded, crc);

    cout << "Generated Codeword: ";
    cout << encoded.substr(encoded.length() - crclen + 1) << endl;
    cout << "Transmitted Message: ";
    cout << data + encoded.substr(encoded.length() - crclen +1)<<endl;
    
    cout << "Enter the message recieved: " << endl;
    string msg;
    cin >> msg;
    msg = xorfun(msg,crc);
    for (char i: msg.substr(msg.length() - crclen +1)){
        if (i != '0') {
            cout << "Error in communication " << endl;
            return 0;
        }
    }

    cout << "No errors in message received" << endl;
    return 0;
}