Byte Packing

[Gajendra]

How does the byte packing and the byte alignment work in VC++ compiler? What is the effect of #pragma pack(n) on the alignment and byte packing
for example while using the structur
struc

double a
char b
char c
}
in a 8 byte packing the sizeof structure is 16. Could anyone explain.

[Carl Daniel [VC++ MVP]]

Gajendra wrote:

How does the byte packing and the byte alignment work in VC++
compiler? What is the effect of #pragma pack(n) on the alignment and
byte packing. for example while using the structure
struct
{
double a;
8 bytes.
char b;
1 byte
char c;
1 byte
6 bytes of padding to make the struct-size a multiple of 8. This is
necessary to ensure that in an array of structs that the 'a' member always
has 8-byte alignment.
};
in a 8 byte packing the sizeof structure is 16. Could anyone explain.

8+1+1+6=16

-cd