The following code print "cba" on certain compilers, Why is this issue happening. Explain. #include  using namespace std; class queue { private: char* s; int F, R, size; public: queue(int i=4) { s= new char[i]; size=i; F=R=-1; } ~queue() { delete []s; } bool empty() { return F==R; } /* bool full()//this is for a non circular queue { if (F==-1 && R==size-1) return true; for (int i=0; i<=F; i++) s[i]=s[F+i+1]; R=R-F-1; F=-1; return false; }*/ bool full() { if ((R+1)%5==F) return true; return false; } /* void add (char c)//non circular add { if (full()) { cout << "queue is full"; exit(1); } R++; s[R]=c; }*/ void add (char c) { if (full()) { cout << "queue is full"; exit(1); } R=(R+1)%size; s[R]=c; } /* char del()// non circular { if (empty()) { cout << "queue empty"; exit(1); } F++; return s[F]; }*/ char del() { if (empty()) { cout << "queue empty"; exit(1); } F=(F+1)%size;//only difference return s[F]; } }; int main() { queue q; q.add('a'); q.add('b'); q.add('c'); cout << q.del() << q.del() << q.del(); return 0; }