memory allocation for structures elements

Question

Hi I am having difficulties in understanding about how the memory is allocated to the structure elements.

For example if i have the below structure and the size of c

Answer 1

This is a compiler dependent behavior. Some compiler makes that 'double' to be stored after 8 bit offset.

IF you modify the structure as below you will get different result.

struct temp
{
double b;  // size is 8
int a;     // size is 4
int e;     // size is 4
double d;  // size is 8
char c;    // size is 4
}

Every programmer should know what padding you compiler is doing. E.g. If you are working on ARM platform and you set compiler settings to do not pad structure elements[ then accessing structure elements through pointers may generate 'odd' address for which processor generates an exception.