Structs and Unions
Structs
- In Computer Systems, structs are collections of heterogeneous data
- laid out in consecutive memory locations (used paddings to ensure alignment)
- reordering can reduce size!
... turns into ...
Paddings
- Elements will be padded to match the size.
- If the struct has
int, 4 bytes in size, it needs to start at a multiple of 4.
Unions
- Union allows elements to read/write in the same memory.
- All elements start at offset 0.
- The size of the union is the biggest member.
- Elements must be plain old data or at least default constructible.
- Bytes can be stored in reversed order depending on the endianness.
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