初始化列表的简单示例

Question

I'm looking for a simple example of how to use the initializer list. Here's what I want to do: I've got the following class:

class foo{
    public:
        void set_x(const int ix);
        void set_y(const int iy);
        void display();
    private:
        int x;
        int y;
};

I'd like to create an object of this class in the following way:

foo fooObj = {1, 2};

I know that it is possible with vector in C++11. How can I implement this kind of behaviour?

Answer 1

In this case, a simple constructor will work:

foo(int x, int y) : x(x), y(y) {}

If the class were an even simpler aggregate (which yours would be if the data members were public) then you wouldn't even need that - this style of initialisation will initialise each member of an aggregate in turn.

For something more complicated, like vector , where the number of arguments can vary, you need to use an initializer_list . Include the header:

#include <initializer_list>

and a constructor

foo(std::initializer_list<int>);

The type acts like a container, with begin() , end() and size() functions to access its contents.