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

In your calculation, you ignore the fact that e is subject to be padded as well:

The struct looks like

0       8       16      24      32
AAAAaaaaBBBBBBBBCcccccccDDDDDDDDEEEEeeee

where uppercase is the variable itself, and lowercase is the padding applied to it.

As you see (and as well from the addresses), each field is padded to 8 bytes, which is the largest field in the structure.

As the structure might be used in an array, and all array elements should be well-aligned as well, the padding to e is necessary.