How can I control the way gcc/g++ automatically includes headers?

Question

I've run into trouble in the past when I've tried porting some C++ code written on Mac OS X to a Linux system, or trying to compile code written against an older version of gcc/g++ with a newer one:

It seems that some (older?) versions of gcc/g++ would automatically include some header files for you.

For example, code that uses printf should require #include <stdio.h>. And code that uses memcpy should require #include <string.h>. But depending on the version of gcc I'm using, it will occasionally include these for me.

It wreaks havoc when I forget to include something and then never get errors until I go to compile the code on another system. At that point it's a game of running all over the project and fixing the includes.

Has anyone else run into this? Is there a way to force gcc to autoinclude or to not autoinclude? Or, is there a way to know what it's autoincluding?

Answer 1

When compiling on different systems, you might meet different problems and not only includes. I would suggest investing in a continuous build system that will compile on all OS you need after each update of the code, so you are rapidly aware of any portability issue.

You can also put all common system header files inside a specific header file you will write and systematically include it in all your files.

Answer 2

Are you sure it's not other headers pulling those one's in, and on the other platforms not doing so?