So, due the fact convert what arrive in char ... so due the fact I don't know what virtualwire send out then I convert every buffer element in char and the I compare the result ... is wrong like thinking ?
I don't understand all of this, but I think that what you are saying is that you are trying to cast the value to a char. That is not how to do it.
text_arrived[i] = (char)buf[i];
I edited my previous response. You should re-read it.