Declaring a struct

public struct Vector 
{
    public int X;
    public int Y;
    public int Z;
}

public struct Point
{
    public decimal x, y;
    
    public Point(decimal pointX, decimal pointY)
    {
        x = pointX;
        y = pointY;
    }
}

• struct instance fields can be set via a parametrized constructor or individually after struct construction.
• Private members can only be initialized by the constructor.
• struct defines a sealed type that implicitly inherits from System.ValueType.
• Structs cannot inherit from any other type, but they can implement interfaces.
• Structs are copied on assignment, meaning all data is copied to the new instance and changes to one of them are not reflected by the other.
• A struct cannot be null, although it can used as a nullable type:

Vector v1 = null; //illegal
   Vector? v2 = null; //OK
   Nullable<Vector> v3 = null // OK

• Structs can be instantiated with or without using the new operator.

//Both of these are acceptable
Vector v1 = new Vector();
v1.X = 1;
v1.Y = 2;
v1.Z = 3;

Vector v2;
v2.X = 1;
v2.Y = 2;
v2.Z = 3;

However, the `new` operator must be used in order to use an initializer:

Vector v1 = new MyStruct { X=1, Y=2, Z=3 }; // OK
Vector v2 { X=1, Y=2, Z=3 }; // illegal

A struct can declare everything a class can declare, with a few exceptions:

• A struct cannot declare a parameterless constructor. struct instance fields can be set via a parameterized constructor or individually after struct construction. Private members can only be initialized by the constructor.
• A struct cannot declare members as protected, since it is implicitly sealed.
• Struct fields can only be initialized if they are const or static.