typedef union _Value { signed char c; unsigned char b; signed short s; unsigned short w; signed long l; unsigned long u; float f; double *d; char *p; } Value; typedef struct _Field { WORD nFieldId; BYTE bValueType; Value Value; } Field; typedef struct _Packet { WORD nMessageType; WORD nSecurityType; BYTE bExchangeId; BYTE bMarketCenter; int iFieldCount; char cSymbol[20]; Field FieldArr[1]; } Packet; What are the C# equivalent of these C++ structs? I am migrating some code from C++ to C# and having problems to migrate these structures. I had tried a few things but I always ended up having marshalling problems.