Include Guards vs #pragma once - MarekBykowski/readme GitHub Wiki

// Traditional include guard — portable, standard C
#ifndef MY_HEADER_H
#define MY_HEADER_H

// ... header content ...

#endif  // MY_HEADER_H

// #pragma once — simpler, supported by GCC/Clang/MSVC, not standard C
#pragma once

// ... header content ...

	Include guard	#pragma once
Standard C	✓	✗ (compiler extension)
GCC / Clang / MSVC	✓	✓
Handles symlinks/copies	✓	✗ (may include twice)
Less boilerplate	✗	✓
Linux kernel uses	✓ guards	—

💡 For embedded/cross-compiler work: use include guards. #pragma once is fine for most projects but fails edge cases with symlinked headers.