Structs are a composite data structure in the C programming language; they consist of primitives such as ints and pointers all placed in memory in an adjacent fashion, such as an array.
My question is, what are structs themselves made out of? Are they a type of array? For example, a hash table can be implemented as an array of linked-lists. In a similar way, what is a struct implemented as? If need be, please explain at the x86 assembly level. Thank you.
At assembly level Structure boils down to a address accessed by offset corresponding to structure member.
Depending on the alignment rule and storage class memory is allocated for instance of structure.
Example:
struct A
{
int a,
char b
}a1;
In above case if you write a1.b = 5 its assembly equivalent would be something:
MOV 5 TO ADDRESS OF a1 + 4 //assuming integer size is 4
struct variables, same as they can for other objects. The struct doesn't have to have an address; the member values could just be held in registers even if it's not optimized away. (e.g. after inlining a function that returns a struct by value).
Commented
Aug 29, 2017 at 7:04