Converting data into a stream of bytes

Hi all,

i am tring to implement modbus communication protocol. Since socket programing have no sense of data type and they operate only with bytes i have to make 4 functions to convert data into stram of bytes. I need to write a function to convert coils (bits) into bytes, to conver char into bytes, to convert intgers into bytes and to convert long into bytes. I dont have any experience how to do this, please help me on this one.

Best regards,
BoSChoW.

 

I have figured out something but a new problem emerged. I have a structure with various types and i want to know the size of each type in order to determine the number of bytes of each variable. So i made something like this:

Code:

typedef struct
{
int a;
short b;
long c;
short e;
int a;
.
.
.
}modbus;

int main()
{
modbus bus;
modbus *busPtr;
busPtr = &bus

int typeSize = sizeof(busPtr->a); // this works
typeSize = sizeof(&busPtr[0]); // this dosent work

//i am tring to achieve something like this
for (int i = 0; i < 4; i++)
{
     typeSize = sizeof(&busPtr[i]); // this dosent work
}
}

Does anybody know how this is done ?

Thanks and best regards,
BoSCHoW.