How to order a list of objects?

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How to order a list of objects?

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#1 by (1 votes)

1

I need help with this. I have a list in which I must store the information of the taxi drivers, in one of the functions I must print a report of taxi drivers who worked overtime, ordered in descending order. I have seen several examples on the internet but none has helped me, this is the code:

void ReporteHorasExtra() {
    for (list<Taxista*>::iterator it = taxistas.begin(); it != taxistas.end(); it++) {
        if ((*it)->horasExtras() > 0) {
            cout << "Nombre:";
            cout<<(*it)->getNombre();
            cout << ' ';
            cout<<(*it)->getApellido();
            cout << ' '<<"Sexo: ";
            if ((*it)->getSexo() == true) {
                cout << "Femenino" << ' ';
            }
            if ((*it)->getSexo() == false) {
                cout << "Masculino" << ' ';
            }
            cout << "Cantidad de horas extra: ";
            cout<<(*it)->horasExtras();
            cout << endl;
        }
    }
}

That's what I have, but I do not know how to order them.

Issue # 1

I have updated the function in the following way, maybe it is very bad and I am sorry for that, but I have not understood completely.

void ReporteHorasExtra() {
        for (list<Taxista>::iterator it = taxistas.begin(); it != taxistas.end(); it++) {
            vector<Taxista> horas(taxistas.size());
            copy(taxistas.begin(), taxistas.end(), horas.begin());

            sort(horas.begin(), horas.end(), [](auto &a, auto &b) { return a->horasExtras() > b->horasExtras(); });
            if ((it)->horasExtras() > 0) {
                cout << "Nombre:";
                cout<<(it)->getNombre();
                cout << ' ';
                cout<<(it)->getApellido();
                cout << ' '<<"Sexo: ";
                if ((it)->getSexo() == true) {
                    cout << "Femenino" << ' ';
                }
                if ((it)->getSexo() == false) {
                    cout << "Masculino" << ' ';
                }
                cout << "Cantidad de horas extra: ";
                cout<<(it)->horasExtras();
                cout << endl;
            }
        }

    }

This is what I have done, but I have obtained these errors.

lista c++ poo

asked by davidllerenav 28.11.2018 в 23:00

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1 answer

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score 1 · Answer 1

As far as I can see, your problem is in the understanding of code; and it's normal because you're looking at the more complicated examples. What if I told you that sorting data is much easier than you think?:

// Empezamos copiando los taxistas en un vector
std::vector<Taxista*> horas(taxistas.size());
std::copy(taxistas.begin(), taxistas.end(), horas.begin());

// Ordenamos
std::sort(horas.begin(), horas.end(),
          [](auto &a, auto &b){ return a->horasExtras() < b->horasExtras(); });

We copy the Taxista* of your list<Taxista*> in a vector<Taxista*> for two reasons:

We do not want to alter the original list.

The sorting algorithm does not work in lists but it works in vectors 1 .

The example code leaves you in horas taxi drivers ordered according to the extra hours they have made. To make the code even easier, I advise you to overload the injection operator in output data flow for Taxista :

std::ostream <<(std::ostream &o, const Taxista &t)
{
    o << "Nombre: " << t. getNombre() << ' ' << t.getApellido() << ' ';
    o << "Sexo: " << (t.getSexo() ? "Femenino" : "Masculino") << ' ';
    o << "Cantidad de horas extra: " << t.horasExtras() << '\n';

    return o;
}

With these changes your reporting function of overtime could look like:

void ReporteHorasExtra() {

    std::vector<Taxista*> horas(taxistas.size());
    std::copy(taxistas.begin(), taxistas.end(), horas.begin());

    std::sort(horas.begin(), horas.end(),
              [](auto &a, auto &b){ return a->horasExtras() < b->horasExtras(); });

    for (const auto &t : horas)
        std::cout << *t << '\n';
}

Much easier to understand, right?

If you want to know why, I encourage you to ask another question.