Box box3 = box1 + box2;

public static 返回類型 operator 運算符(參數(shù)列表)
{
    // 實現(xiàn)邏輯
}

class Box
{
    private double length;
    private double breadth;
    private double height;

    public double GetVolume()
    {
        return length * breadth * height;
    }

    public void SetLength(double len) => length = len;
    public void SetBreadth(double bre) => breadth = bre;
    public void SetHeight(double hei) => height = hei;

    // 重載 +
    public static Box operator +(Box b, Box c)
    {
        Box box = new Box();
        box.length = b.length + c.length;
        box.breadth = b.breadth + c.breadth;
        box.height = b.height + c.height;
        return box;
    }
}

Box3 = Box1 + Box2;

Box3 = Box.Add(Box1, Box2);

public static bool operator ==(Box lhs, Box rhs)
{
    return lhs.length == rhs.length &&
           lhs.breadth == rhs.breadth &&
           lhs.height == rhs.height;
}

Box a = new Box();
Box b = new Box();
Console.WriteLine(a == b); // False

public override bool Equals(object obj)
public override int GetHashCode()

Box3 = Box1 + Box2;

Box3 = Box.operator +(Box1, Box2);

public class Box : IEquatable<Box>, IComparable<Box>
{
    public double Length { get; set; }
    public double Breadth { get; set; }
    public double Height { get; set; }

    public double Volume => Length * Breadth * Height;

    public static Box operator +(Box a, Box b)
    {
        return new Box
        {
            Length = a.Length + b.Length,
            Breadth = a.Breadth + b.Breadth,
            Height = a.Height + b.Height
        };
    }

    public static bool operator ==(Box a, Box b)
    {
        if (ReferenceEquals(a, b)) return true;
        if (a is null || b is null) return false;
        return a.Equals(b);
    }

    public static bool operator !=(Box a, Box b) => !(a == b);

    public bool Equals(Box other)
    {
        if (other is null) return false;
        return Length == other.Length &&
               Breadth == other.Breadth &&
               Height == other.Height;
    }

    public override bool Equals(object obj)
        => Equals(obj as Box);

    public override int GetHashCode()
        => HashCode.Combine(Length, Breadth, Height);

    public int CompareTo(Box other)
        => Volume.CompareTo(other.Volume);
}

public static Box operator +(Box b, int x)