THINK++ — Engineering Visualized

Safe Includes

Header Guards

Prevents a header file from being included multiple times in the same translation unit, which would otherwise cause "redefinition" errors.

TRADITIONAL METHOD

#ifndef MY_HEADER_H
#define MY_HEADER_H

// Header content here

#endif

MODERN METHOD

#pragma once

Non-standard but supported by almost all modern compilers. Much cleaner and less error-prone.

WHY DO WE NEED THIS?

If File A and File B both include utils.h, and then File C includes both A and B, without header guards, utils.h would be included twice in C, leading to errors.

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