Hi Volkan,

RCSTM8 uses byte-alignment for structure members, so you do not have to mind about this. This is because the STM8 data bus does not suffer from misaligned data, so there is no need to align RAM data (Flash data should be 16-bit aligned on STM8 for fastest access)

Note however that it is a good rule to follow as simple as this: Align structure members on a multiple of their own size. This means that "char" variables can go wherever you like (8-bit aligned), 'short' should be aligned on 16-bit and long/float should be 32-bit aligned. This will make your structures portable and fast on most architectures.

So your second example is better if code portability is a concern.

Another side rule is to place largest structure members first (except for arrays), so your third (best) solution would probably be:

struct s_Example3 {
   long l_variable3;
   int i_variable2;
   char c_variable1;
   char c_variable4;
};

Also 2 notes (just for fun):
- 'int' is not portable, you may prefer using 'short'.
- 'char' is not portable, you should explicitly have 'signed char' or 'unsigned char'.

Enjoy,
Bruno