Question

I got the following struct:

struct Packet
{
    short PacketSize;
    short Type;
};

struct SizeValidity
{
    short SizeEnc;
};

struct SendEncSecureCode
{
    Packet header;
    short EncSecurityToken;
    int lTime;
    SizeValidity ending;
};

And on my code i want to get the size of the struct with the sizeof operator like this:

SendEncSecureCode sendpacket;
sendpacket.header.PacketSize = sizeof SendEncSecureCode;

Problem is i always get size 0x10 instead of 0x0C i am specting, so i change the INT type to DWORD and still the same problem, later i try with DWORD32 and still the same, the compiler is setting it as 8 bytes. I am working on VC11 Beta and the soft is aim to x86 not x64. Thanks

Answer 1

To get the size you’re expecting, you can tell the compiler to use 1-byte packing:

#pragma pack(push, 1)
struct Packet
{
    short PacketSize;
    short Type;
};

struct SizeValidity
{
    short SizeEnc;
};

struct SendEncSecureCode
{
    Packet header;
    short EncSecurityToken;
    int lTime;
    SizeValidity ending;
};
#pragma pack(pop)

Please see http://vcfaq.mvps.org/lang/11.htm