komunikator

#include <iostream>

using namespace std;

class komunikator {
public:
    static int liczba_obiektow;
    komunikator(){liczba_obiektow++; }
    virtual ostream& wyswietl(ostream& out) const = 0;
    virtual void operator+=(const string& a) const = 0;

 virtual ~komunikator(){ liczba_obiektow--; }
};

int komunikator::liczba_obiektow = 0;

class k1 : public komunikator {
protected:
    string* txt;
public:
    k1():txt(new string("----")){}
    k1(const string& a1): txt(new string(a1)) {}
    k1(const k1&r): txt(new string(*r.txt)){}

    k1& operator=(const k1& r) {
        if (this != &r) {
            delete txt;
            txt = new string(*r.txt);
        }
        return *this;
    }

    void operator+=(const string& a)const {
        *txt += a;
    }

    ostream& wyswietl(ostream& out)const { return out << *txt; }
    ~k1() { delete txt; }
};

class k2 : public k1 {
    int l;
public:
    k2():k1(), l(0) {}
    k2(const string& a1, const int& a2) :k1(a1),l(a2){}

    ostream& wyswietl(ostream& out)const {
        if (*txt == "----" && l == 0) throw string("brak danych\n");
        return out << *txt<< " " << l; }



    friend k2& operator+=(k2& a1, const int& p);



};

k2& operator+=(k2& a1, const int& p){

    a1.l += p;
    return a1;
}


ostream& operator<<(ostream& out, const komunikator& r) {
    return r.wyswietl(out) << endl;
}



int main()
{
    const k1 koniec("Koniec komunikatow");

    komunikator* linia[5];
    linia[0] = new k1("Temperatura powietrza");
    linia[1] = new k2("Czestochowa", -5);
    linia[2] = new k1("Opady sniegu");
    linia[3] = new k2("Katowice", 10);
    linia[4] = new k1(koniec);

    for (int i = 0; i < 5; ++i)
        cout << *linia[i];

    cout << "************* 3 ************" << endl;

    *linia[0] += " [ oC ]:";
    *linia[2] += " [ cm ]:";
    *(static_cast<k2*>(linia[1])) += 2;
    *(static_cast<k2*>(linia[3])) += 2;

    for (int i = 0; i < 5; ++i) {
        cout << *linia[i];
        delete linia[i];
    }

    cout << "************* 4 ************" << endl;

    cout << "Liczba dialajacych komunikatorow :"
        << komunikator::liczba_obiektow << endl;

    linia[0] = new k1("Temperatura powietrza");
    linia[1] = new k2;
    linia[2] = new k1("Opady sniegu");
    linia[3] = new k2;
    linia[4] = new k1(koniec);

    cout << "Liczba dialajacych komunikatorow :"
        << komunikator::liczba_obiektow << endl;

    for (int i = 0; i < 5; ++i) try{
        cout << *linia[i];
        delete linia[i];
    }
    catch (const string & r) { cout << r; }

    cout << "************* 5 ************" << endl;
    return 0;
}