How to create a struct and initialize it at the same time?

Question

The struct is defined like this:

 struct Edge {
    int weight;
    Vertex* v1;
    Vertex* v2;
  };

I need to do something like

new Edges(v1, v2, v3);

but that could only be done with a "class" and using ctor. How can I create a new element of struct and initialize it at the same time?

Thanks!

Why use `new` at all? Anyway, you're looking for aggregate initialization. — chris, Dec 11 '12 at 07:04
I tried to do something like v[v1].edges.push_back(new Edges(v1, v2, v3)); and edges is defined as list edges; — JASON, Dec 11 '12 at 07:06

score 2 · Accepted Answer · edited May 23 '17 at 12:03

2

You can write a constructor for a struct as well in C++. A C struct is very limited, but in C++ there exists only 2 differences between struct and class.

In class all members are by default private, in struct all members are by default public.
Inheritance from struct defaults to public while class defaults to private

Thanks @gil_bz and @icepack

edited May 23 '17 at 12:03

Community

1
1

answered Dec 11 '12 at 07:07

Karthik T

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To be more specific, there is NO difference between structs and classes in C++, besides the default accessibility for members (public for structs, private for classes) – gil_bz Dec 11 '12 at 07:11
1

And default inheritance from `struct` is `public` instead of `private` for `class`. – SomeWittyUsername Dec 11 '12 at 07:17
Your differences between `struct` and `class` are not completely right. – juanchopanza Dec 11 '12 at 07:26

score 0 · Answer 2 · answered Dec 11 '12 at 07:13

You need to create a parameterized constructor. Do it this way

struct Edge
{
    int weight;
    Vertex* v1;
    Vertex* v2;

    Edge(int a_weight, Vertex *a_v1, Vertex *a_v2)
    {
        weight = a_weight;
        v1 = a_v1;
        v2 = a_v2;
    }
};

Then create object like this:

Edge e(9, v1, v2);

How to create a struct and initialize it at the same time?

2 Answers2