The best practice for including header files to multiple inherited classes

Question

Let's say we have a parent class with header parent.h and 2 child classes child1.h and child2.h, since they both inherit from parent, both header files should include parent.h. Including child1.h and child2.h in another file will result of a duplicate definition of the parent class. What is the best way to avoid this? Is using #pragma once a good practice, or are there other ways to fix this?

score -1 · Accepted Answer · answered Oct 01 '18 at 16:35

-1

This is the exact reason why #ifndef is used as a check in header files.

For example, your `parent.h' may have:

#ifndef PARENT_H
#define PARENT_H

.... //Your header definition

#endif

Then, in child1.h and child2.h

#ifndef PARENT_H
#include "parent.h"
#endif

....//Your source code

answered Oct 01 '18 at 16:35

Susmit Agrawal

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You do not need or want that `#ifndef` in the child headers. – Oct 01 '18 at 16:39
so how do you do it instead? – Omar Mneimneh Oct 01 '18 at 16:43
1

@Omar Simply have each header file have its own include guards. Other files should not know or care what the names of those guards are. – Oct 01 '18 at 16:45

score -1 · Answer 2 · answered Oct 01 '18 at 16:41

-1

Yes, you can use pragma or #ifndef

#ifndef _AUTOMOBILE_H
#define _AUTOMOBILE_H
//...
#endif

answered Oct 01 '18 at 16:41

codeHero

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Names like `_AUTOMOBILE_H` which begin with an underscore and an uppercase letter are reserved for the C++ implementation - you should not be creating them in your own code. Simply use `AUTOMOBILE_H` – Oct 01 '18 at 16:43

The best practice for including header files to multiple inherited classes

2 Answers2