How do I compile/create a ruby extension that uses c?

Question

Hi all,

I want to create a ruby extension that uses c. But when I compile it with gcc, I am getting this error:

gcc rubyext.c -orubyext -I /usr/local/include/ruby-1.9.1/

In file included from rubyext.c:1:
/usr/local/include/ruby-1.9.1/ruby/ruby.h:25:25: error: ruby/config.h: No such file or directory
In file included from rubyext.c:1:
/usr/local/include/ruby-1.9.1/ruby/ruby.h:107: error: ‘SIZEOF_INT’ undeclared here (not in a function)
/usr/local/include/ruby-1.9.1/ruby/ruby.h:108: error: ‘SIZEOF_LONG’ undeclared here (not in a function)
/usr/local/include/ruby-1.9.1/ruby/ruby.h:112: error: ‘SIZEOF_VOIDP’ undeclared here (not in a function)
In file included from /usr/local/include/ruby-1.9.1/ruby/ruby.h:1326,
                 from rubyext.c:1:
/usr/local/include/ruby-1.9.1/ruby/missing.h:25: error: redefinition of ‘struct timeval’
/usr/local/include/ruby-1.9.1/ruby/missing.h:35: error: redefinition of ‘struct timespec’
In file included from /usr/local/include/ruby-1.9.1/ruby/intern.h:27,
                 from /usr/local/include/ruby-1.9.1/ruby/ruby.h:1327,
                 from rubyext.c:1:
/usr/lib/gcc/x86_64-linux-gnu/4.4.3/include/varargs.h:4:2: error: #error "GCC no longer implements <varargs.h>."
/usr/lib/gcc/x86_64-linux-gnu/4.4.3/include/varargs.h:5:2: error: #error "Revise your code to use <stdarg.h>."
In file included from /usr/local/include/ruby-1.9.1/ruby/intern.h:29,
                 from /usr/local/include/ruby-1.9.1/ruby/ruby.h:1327,
                 from rubyext.c:1:
/usr/local/include/ruby-1.9.1/ruby/st.h:122: error: expected declaration specifiers or ‘...’ before ‘uint32_t’
In file included from /usr/local/include/ruby-1.9.1/ruby/ruby.h:1327,
                 from rubyext.c:1:
/usr/local/include/ruby-1.9.1/ruby/intern.h:508: error: expected declaration specifiers or ‘...’ before ‘rb_pid_t’
/usr/local/include/ruby-1.9.1/ruby/intern.h:526: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘rb_fork’
/usr/local/include/ruby-1.9.1/ruby/intern.h:527: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘rb_fork_err’
/usr/local/include/ruby-1.9.1/ruby/intern.h:529: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘rb_waitpid’
/usr/local/include/ruby-1.9.1/ruby/intern.h:530: error: expected ‘)’ before ‘pid’
/usr/local/include/ruby-1.9.1/ruby/intern.h:531: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘rb_spawn’
/usr/local/include/ruby-1.9.1/ruby/intern.h:532: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘rb_spawn_err’
/usr/local/include/ruby-1.9.1/ruby/intern.h:534: error: expected ‘)’ before ‘pid’
/usr/local/include/ruby-1.9.1/ruby/intern.h:652: error: expected declaration specifiers or ‘...’ before ‘uint32_t’

Did I do it wrong? My rubyext.c file only has one line of code:

#include <ruby.h>

Any help is greatly appreciated.

Answer 1

Of course you cannot just include the header files, you must link to the Ruby library.

Read This chapter from the Pickaxe.

Also feel free to browse some of my repos on github, I write a lot of C extensions.

Send me a message on that site if you need help.