//Sequential，按最大成员长度进行对齐，占用内存将是 最大长度成员的整数倍长度[StructLayout(LayoutKind.Sequential)]struct Struct1{    public short Short1;    public int Int1;    public short Short2;}//总共占用12字节，每行4字节，两个short各占一半，剩余填充，int占一行1 Short1  | --------2        Int13 Short2  | --------//如果 int 改为 long，占用内存将变为 24字节=8*3[StructLayout(LayoutKind.Sequential)]struct Struct1{       public int Int1;    public short Short1;    public short Short2;}//每行4字节，两个short占行，int占一行1      Int12 Short1 | Short2//如果 int 改为 long，占用内存将变为 16字节=8*2

 //总共8字节  Int1占0-3，Short1占4-5，Short2占6-7， [StructLayout(LayoutKind.Explicit)] struct Struct1 {        [FieldOffset(0)]     public int Int1;     [FieldOffset(4)]     public short Short1;     [FieldOffset(6)]     public short Short2; }