How to find an object with specific field values in a std::set?

Question

I call a method which returns std::set const& where T is a class type. What I\'m trying to achieve is to check whether the set contain

Answer 1

You'll want std::find_if, with a predicate function object that checks the properties you're interested in. It might look something like this:

struct FindCar {
    FindCar(Colour colour, int doors, double top_speed) :
        colour(colour), doors(doors), top_speed(top_speed) {}

    bool operator()(Car const & car) const {
        return car.colour == colour
            && car.doors == doors
            && car.top_speed == top_speed;
    }

    Colour colour;
    int doors;
    double top_speed;
};

std::set const & cars = get_a_set_of_cars();
std::set::const_iterator my_car =
    std::find_if(cars.begin(), cars.end(), FindCar(Red, 5, 113));

In C++0x, you could replace the "FindCar" class with a lambda to make the code a bit shorter.