struct sizeof result not expected

Question

I have a a struct defined thusly:

typedef struct _CONFIGURATION_DATA {
    BYTE configurationIndicator;
    ULONG32 baudRate;
    BYTE stopBits;
    BYTE par         


        

Answer 1

The extra size you are measuring is the padding introduced by the compiler.

Presumably, you are working on a 32 bits system, so you will have 3 bytes of padding between configurationIndicator and baudRate, and 3 more bytes of padding at the end of the struct.