This content originally appeared on DEV Community and was authored by Harshita Sharma D
This is a submission for DEV Computer Science Challenge v24.06.12: One Byte Explainer.
Explainer
Structure padding: Like neatly lining books on a shelf, compilers add empty bytes (padding) between struct members for faster processor access. This can make structs larger than expected!
Additional Context
Consider this code:-
#include <iostream>
struct Data {
char c; // 1 byte
int i; // 4 bytes (assuming 32-bit system)
};
int main() {
std::cout << sizeof(Data) << std::endl; // Might be > 5!
}
Explanation:
- This code defines a Data struct with a char and an int.
- Similar to the previous example, we use
sizeof(Data)to print the struct size. Here, padding might occur to ensure the int aligns with its preferred boundary (often 4 bytes on 32-bit systems). - The expected size would be 1 (char) + 4 (int) = 5 bytes. However, the actual size might be greater due to padding.
- If you ask me, then it will be 8 bytes, since we are assuming a 32-bit system that will read the memory in the chunks of 4 bytes. This does not allow other variables to take the left 3 bytes (8-5) space. Hence 8 bytes will get occupied by the object of struct
Datafor faster processor access.
Note:
The exact amount of padding can vary depending on the compiler and target architecture.
- This image is generated using the prompt:- "Alan Turing, the computer scientist, explaining the concept of structure padding in C++ pride month color palette rainbow color"
This content originally appeared on DEV Community and was authored by Harshita Sharma D
Harshita Sharma D | Sciencx (2024-06-24T03:35:29+00:00) Computer Science Challenge – Structure Padding. Retrieved from https://www.scien.cx/2024/06/24/computer-science-challenge-structure-padding/
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