How are the data elements of a structure accessed and processed explain?

Answer 1

The data elements of a structure are laid out according to the order they are declared. Padding bytes may also be inserted between members to ensure all members are correctly aligned. Memory alignment can be user-defined, however it's generally better to align objects according to the underlying architecture. For instance, on a 32-bit system the underlying architecture has a 4-byte word length, thus an object that is equal or greater in length is best aligned upon a 4-byte boundary to keep memory access cycles to a minimum. Types that are smaller than the word length are usually aligned so that they do not cross a word boundary, such that a single 4-byte word can store 4 char types, 2 shorts, or 2 chars and 1 short. If the total size of the structure crosses a word boundary, padding bytes are inserted after the final member so the total size is an exact multiple of the word length. However, if the total size is less than a single word length to the extent that two or more structures may fit within a word, no padding bytes are required.

Given that each structure member is positioned at a constant zero-based offset from the start address of the structure, the compiler can use trivial pointer arithmetic to access the individual members of an instance of the structure, just as easily as it can calculate the address of an array element from its zero-based suffix (index).