在C ++中，如何为向量中的每个元素创建一个新对象？

Question

Suppose I've got this class:

class dog
{
    public:
        //dogstuff
    private:
        //secret dogstuff
};

and then I've got a function that searches through something unrelated and gets me an UNKNOWN NUMBER OF DOG NAMES:

dogNamesVector = getListOfDogNames();

So, the list of dog names might be something like "Spike, Spot, George, Shadow, ect..".

Is there a smart way to then go:

dog DOGNAME()

and get a bunch of dog objects that I can call and use with the list of dog names?

Answer 1

So, lets say you have a vector of dogs:

    vector<dog> dogs {...};

And we will assume that there are already dogs in this vector. That would mean that you already have objects of type dog, and to call them, all you would need to do is use the bracket notation:

    dogs[i];

If you wanted to assign this dog to another object, you would use:

    dog spike = dogs[i];

If you wanted a unique name (key, or identifier) you would include that in the class itself, as such:

    private:
        string dog_name;

And to access that, you would make a member function (or 'method'). Combine any of these steps with some form of loop (any form of iteration will do) and you can create as many dog objects as needed, and you can also create a function to search by name if that's something that would help you.

Answer 2

If you have a list of strings, and your dog class can be constructed with a string as input, you can construct a vector of dog objects using iterators to the string list, eg:

class dog
{
public:
    dog(const std::string name) : m_name(name) {}
private:
    std::string m_name;
};

std::vector<std::string> dogNames = getListOfDogNames();

std::vector<dog> dogs(dogNames.begin(), dogNames.end());

Demo

Answer 3

std::vector<dog> dogs = get_dogs();
std::vector<std::string> dog_names;

dog_names.reserve(dogs.size());

std::transform(std::begin(dogs), std::end(dogs), std::back_inserter(dog_names), [](auto const& dog) { return dog.name(); });