C#实现联合体

        [StructLayout(LayoutKind.Explicit, Size = )]
        public struct TypeTransform
        {
            [FieldOffset()]
            public float f;

            [FieldOffset()]
            public int i;

            [FieldOffset()]
            public double d;

            [FieldOffset()]
            public long l;

            //[FieldOffset(0)]
            //public byte b1;

            //[FieldOffset(1)]
            //public byte b2;

            //[FieldOffset(2)]
            //public byte b3;

            //[FieldOffset(3)]
            //public byte b4;
        }