Preventing Multiple Header Inclusion

To prevent multiple inclusion of header files, you can use either header guards or the #pragma once directive.

Header Guards

Header guards work by checking if a unique macro is defined. If it's not defined, the header content is included, and the macro is defined to prevent subsequent inclusions.

1// MyHeader.h
2#ifndef MYHEADER_H
3#define MYHEADER_H
4
5// Header content goes here
6
7#endif

#pragma once

The #pragma once directive tells the compiler to include the header file only once during compilation. It's a simpler alternative to header guards.

1// MyHeader.h
2#pragma once
3
4// Header content goes here

Best practices:

• Use either header guards or #pragma once in all your header files.
• Choose a consistent naming convention for header guards (e.g., MYPROJECT_MYHEADER_H).
• Prefer #pragma once if your compiler supports it, as it's more concise and less error-prone.

By following these practices, you can avoid common issues like redefinition errors and circular dependencies caused by multiple header inclusions.