Include Coding Standard

[Precious roy]

Hi all,

my question is quite easy, but i cant really find a yes or no answer.

when including files where would you generally put your includes?

Example One:

a.h:
#pragma once
#include <string>
#include <vector>

#include "b.h"

class a
{
//..... code
}

a.cpp
#include "a.h"

//.....code 

Example Two:

a.h:
#pragma once
class a
{
//..... code
}

a.cpp
#include <string>
#include <vector>

#include "a.h"
#include "b.h"

//.....code 

so which would be the better choice?

[Smac89]

Example Two is better. You should generally avoid having to depend on libraries needed by your program to be declared in other files. The main file has #pragma once enabled; so even if you declare all the libraries needed by main program in, in anther file, including them in your main will not incur any overhead

[Precious roy]

so if i understand correctly you need to do all the includes in the cpp files?

[Smac89]

yes, you can also include them in the header files, but they should all be included in the main file

[Cubbi]

I go with
a.h:

#ifndef INCLUDED_A_H
#define INCLUDED_A_H
class a
{
//..... code
}
#endif // INCLUDED_A_H 

a.cpp

#include "a.h"
#include "b.h"
#include <string>
#include <vector>

//.....code  

(pragma is non-standard, and I include project files before library files to expose hidden dependencies)