How to build C program with Lua

Question

test.c :

#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"

int main(){

  lua_State *L = luaL_newState();  /* opens Lua */
  luaL_openlibs(L);   /* opens the standard libraries */

  luaL_dofile(L,"test.lua"); /* runs Lua scrip */

  lua_close(L);
  return 0;

}

build:

gcc -o test test.c -I/usr/local/Cellar/lua/5.1.5/include

then i got error:

test.c:7:18: warning: implicit declaration of function 'luaL_newState' is
      invalid in C99 [-Wimplicit-function-declaration]
  lua_State *L = luaL_newState();  /* opens Lua */
                 ^
test.c:7:14: warning: incompatible integer to pointer conversion initializing
      'lua_State *' (aka 'struct lua_State *') with an expression of type 'int'
      [-Wint-conversion]
  lua_State *L = luaL_newState();  /* opens Lua */
             ^   ~~~~~~~~~~~~~~~
2 warnings generated.
Undefined symbols for architecture x86_64:
  "_luaL_loadfile", referenced from:
      _main in test-dxPwkn.o
  "_luaL_newState", referenced from:
      _main in test-dxPwkn.o
  "_luaL_openlibs", referenced from:
      _main in test-dxPwkn.o
  "_lua_close", referenced from:
      _main in test-dxPwkn.o
  "_lua_pcall", referenced from:
      _main in test-dxPwkn.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

I installed Lua via Homebrew:

ls /usr/local/Cellar/lua/5.1.5/include
lauxlib.h lua.h     lua.hpp   luaconf.h lualib.h

Anyone knows how to solve this error? Thanks.

You need to add either the import library or the lua*.so shared object when building your example. The undefined refs comes from the linker not know where those lua C functions are. I'm not sure where this would be on your linux setup. Maybe try a which lua51.so or look in one of your bin directories. Also move your -I parameter before test.c and that should fix the warnings. — greatwolf
– greatwolf, Commented Dec 8, 2013 at 6:36

lhf · Accepted Answer · 2013-12-08 11:32:23Z

5

It's luaL_newstate, not luaL_newState.

You also need -llua -lm at the end of the command line.

answered Dec 8, 2013 at 11:32

lhf

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freedoo · Accepted Answer · 2013-12-08 06:55:51Z

0

when u make it, u should ld the .so file of lua which may be in /usr/local/lib, find out it, and use the -L to add the library path, use -l to link the library.

finally, after the make step, if the program cannot run, u should also use ln -s to add a symbol link which is related to the .so in /usr/lib.

answered Dec 8, 2013 at 6:55

freedoo

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