How to include custom .h files in /usr/include

Question

I have some custom .h files placed under /usr/include, but in a directory (/usr/include/itsmag1c), and I'm trying to include them in my C file. I'm guessing that because I use

#include "filename.h";

for files in the same directory, and I would use angle brackets for including a file like math.h or stdio.h. Am I right in guessing that I would use the angle brackets for including my custom header files? If so, my program wont compile, I get the error that the included files cannot be found. Can someone please point to me how I would include these files, or would it be best to have them in the same directory as my program?

Dirk is no longer here · Accepted Answer · 2012-04-12 20:54:11Z

4

Two choices:

Use #include <itsmagic1c/filename.h>
Use #include <filename.h> as before but add a -I switch.

Boost etc use method 1. (which works well provided you have Boost installed in system locations as you would on a reasonably standard Linux box with reasonable package management).

Method 2. is fine too, but more work on the build system, Makefiles, etc.

answered Apr 12, 2012 at 20:54

Dirk is no longer here

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2 Comments

ergosys Over a year ago

The first provides some isolation between components, so it's the better choice.

DiCaprio Over a year ago

if I add a folder to /usr/include/ do i need to reboot in order to have gcc find it?

Rob · Accepted Answer · 2012-04-12 20:54:44Z

2

Usually, you would put your own headers in the same directory or in a subdirectory. Same-dir includes work with "". For bracket includes, if you use gcc, you can pass additional include directories with

  -Irelativedir

or

  -I/usr/local/yourpath.

answered Apr 12, 2012 at 20:54

Rob

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2 Comments

Matthew Over a year ago

I have them in the /usr/local directory because more than one of my programs use the .h files, and they are packaged with all my programs, but only copied if they are not already present.

Wander Nauta Over a year ago

The -I option is supported by tcc, clang and icc as well. Microsoft's compilers use /I.

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