The error is occurring because you are trying to compare a single character (char) to a string ("red") in this line:


if (signal == "red")


To fix this, you should compare signal to a character instead of a string. For example:


if (signal == 'r')
{
    cout << "don't go! Plz stop!" << endl;
}


Alternatively, if you want to compare signal to a string, you should declare signal as a string type instead of a char type. Here's an example:


string signal;
cout << "enter signal name:" << endl;
cin >> signal;
if (signal == "red")
{
    cout << "don't go! Plz stop!" << endl;
}
cout << "once the signal is green then you can go:)" << endl;


This way, you can compare signal to strings without any conversion errors.