How to print from a vector?

sea711 (19)
How to print from this vector?

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    //Cars
    vector <Car> ParkingLot;
    ParkingLot.push_back(Car(234, 4, 2, EColor::NOCOLOR, "Sibble"));
    ParkingLot.push_back(Car(457.1, 4, 4, EColor::PURPLE, "Sal"));
    ParkingLot.push_back(Car(3423.8, 4, 3, EColor::BLUE, "Susan"));


I thought this:
cout << Car.ParkingLot(0);
but it doesn't work. Any body know?
Last edited on
Chervil (7320)
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#include <iostream>
#include <fstream>
#include <vector>
#include <cstdlib>

    using namespace std;

int main()
{
    vector <int> numbers;

    numbers.push_back(rand() % 100);
    numbers.push_back(rand() % 100);
    numbers.push_back(rand() % 100);

    cout << "\none\n";
    for (unsigned int i=0; i<numbers.size(); i++)
    {
        cout << numbers[i] << endl;
    }

    cout << "\ntwo\n";
    for (vector<int>::iterator it = numbers.begin(); it!=numbers.end(); it++)
    {
        cout << *it << endl;
    }

    cout << "\nthree\n";
    for ( auto n : numbers)
    {
        cout << n << endl;
    }
}

Output:

one
41
67
34

two
41
67
34

three
41
67
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ShodanHo (110)
The simple way, print from vector<Car>:

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std::ostream&
operator<<(std::ostream& os, const std:vector<Car>& vc)
{
  os << '[';
  for (auto itr = vc.cbegin(); itr != vc.cend(); ++itr) {
    if (itr != vc.cbegin())
      os << ',';
    os << *itr;
  }
  os << ']';
  return os;
}


Slightly more complex, use template to print from vector of any class:

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template <class T>
std::ostream& operator<<(std::ostream& os, const vector<T>& v)
{
  os << '[';
  for (auto itr = v.cbegin(); itr != v.cend(); ++itr) {
    if (itr != v.cbegin())
      os << ',';
    os << *itr;
  }
  os << ']';
  return os;
}


And more complex, use template to print from any collection of any class.
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template < template<class,class> class C, class T>
std::ostream& operator<<(std::ostream& os, const C<T, std::allocator<T> >& c)
{
  os << '[';
  for (auto itr = c.cbegin(); itr != c.cend(); ++itr) {
    if (itr != c.cbegin())
      os << ',';
    os << *itr;
  }
  os << ']';
  return os;
}

But, more accurately, any collection with two template class parameters such as list and vector, and not map, multimap, set and multiset.
Refer:
http://www.cplusplus.com/reference/list/list/
http://www.cplusplus.com/reference/vector/vector/
http://www.cplusplus.com/reference/map/map/
http://www.cplusplus.com/reference/map/multimap/
http://www.cplusplus.com/reference/set/set/
http://www.cplusplus.com/reference/set/multiset/

In all cases you have to provide a streaming operator for your class Car:

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std::ostream&
operator<<(std::ostream& os, const Car& car)
{
  os << '(' << car.cost << ','
        << car.wheels << ',' << car.doors << ','
        << car.color << ',' << car.make << ')'; // obviously change to suite
  return os;
}

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