C# Structs: Unassigned local variable?

Question

From the documentation:

Unlike classes, structs can be instantiated without using a new operator.

So why am I getting this error

Answer 1

It is still uninitialized. You need to initialize it before using it. You can use default operator for that if you don't want to create a static Vec.Empty value and happy with the defaults for the structs members:

Vec2 x = default(Vec2);

Mitch Wheat:

This, however doesn't:

public struct Vec2
{
    int x;
    int y;

   public float X { get { return x; } set { x = value; } }
   public float Y { get { return y; } set { y = value; } }

}
static void Main(string[] args)
{
    Vec2 x;

    x.X = 1;
    x.Y = 2; 
}

The compiler prevents you from calling propertis on types before all of it's members have been initialized, even though a property might just set one of the values. The solution, as Jon Skeet proposed, is to have an initializing constructor and preferably no setters.