string databits;

cout<<"Enter data bits: ";

cin>>databits;

int len=databits.length();

string codeword="";

string errorword="";

string correctword="";

float prob=0.50;

int errors=0;

int times=len/4;

int er[10]={0};

int a=0;

for(int i=0;i<len;i+=4){

string dataword="";

string temp="";

for(int j=i;j<i+4;j++){

temp+=databits.at(j);

}

for(int k=0;k<3;k++){

dataword+=temp.at(k);

}

dataword+=" ";

dataword+=temp.at(3);

int p1,p2,p3;

p1=dataword.at(0)^dataword.at(2)^dataword.at(4);

p2=dataword.at(0)^dataword.at(1)^dataword.at(4);

p3=dataword.at(0)^dataword.at(1)^dataword.at(2);

dataword.at(3)=p3;

dataword+=p2;

dataword+=p1;

cout<<a+1<<" Token: "<<dataword<<endl;

codeword+=dataword;

int index=0;

for(int i =0 ; i<dataword.length() ; i++)

{

if( ((float) rand() / (RAND_MAX)) <=prob )

{

if(dataword.at(i)=='0')

{

dataword.at(i)= '1';

errors++;

index=i;

break;

}

else

{

dataword.at(i) = '0';

errors++ ;

index=i;

break;

}

}

}

er[a]=index;

a++;

errorword+=dataword;

}

cout<<endl;

cout<<"Sent CodeWord: "<<endl;

cout<<codeword<<endl<<endl;

cout<<"Received frame:"<<endl;

cout<<errorword<<endl<<endl;

cout<<"Errors: "<<errors<<endl;

int l=errorword.length();

int k=0;

for(int i=0;i<l;i+=7){

string temp="";

for(int j=i;j<i+7;j++){

temp+=errorword.at(j);

}

cout<<"For "<<k+1 <<" token, error is at position "<<er[k]<<endl;

if(temp.at(er[k])=='0'){

temp.at(er[k])='1';

}

else{

temp.at(er[k])='0';

}

correctword+=temp;

k++;

}

cout<<endl;

cout<<"AFTER CORRECTING ALL THE ERRORS:"<<endl;

cout<<correctword<<endl;

return 0;