CODEWITHSUNDEEP
c++lua
Q2Ftb3k
Q2Ftb3k

Reputation: 688

C++ Lua 5.1 Issue

#include <stdio.h>
#include <string.h>
#include <lua.h>
#include <lauxlib.h>
#include <lualib.h>

    int main (void) {
      char buff[256];
      int error;
      lua_State *L = lua_open();   /* opens Lua */
      luaL_openlibs(L);

      while (fgets(buff, sizeof(buff), stdin) != NULL) {
        error = luaL_loadbuffer(L, buff, strlen(buff), "line") ||
                lua_pcall(L, 0, 0, 0);
        if (error) {
          fprintf(stderr, "%s", lua_tostring(L, -1));
          lua_pop(L, 1);  /* pop error message from the stack */
        }
      }

      lua_close(L);
      return 0;
    }

This seems to propagate several errors such as:

error LNK2019: unresolved external symbol "char const * __cdecl lua_tolstring(struct lua_State *,int,unsigned int *)" (?lua_tolstring@@YAPBDPAUlua_State@@HPAI@Z) referenced in function _main main.obj

What's wrong?

Upvotes: 1

Views: 2836

Answers (5)

byronbautista
byronbautista

Reputation: 21

Encountered this linking error and I Had to change the 

#define LUA_API extern

to

#define LUA_API extern "C"

I'm using Lua 5.1 BTW

Upvotes: 2

Gordon
Gordon

Reputation: 1914

Lua 5.1 has lua.hpp:

// lua.hpp
// Lua header files for C++
// <<extern "C">> not supplied automatically because Lua also compiles as C++

extern "C" {
#include "lua.h"
#include "lualib.h"
#include "lauxlib.h"
}

Just #include <lua.hpp>.

Upvotes: 6

Matt
Matt

Reputation: 1211

The Lua files are in C so you have to use

extern "C" { #include "luafiles.cpp" }

You are just getting linker errors.

Upvotes: 0

Necrolis
Necrolis

Reputation: 26171

You need to wrap the lua headers in extern "C" to get the correct symbol linkages, as well as linking to the lib(if your not compiling it into the project)

Upvotes: 6

dutt
dutt

Reputation: 8209

Probably nothing wrong with your code, you have a linking problem, it can't find the function definition for lua_tolstring. Add the lua library when linking and you should be fine.

Upvotes: 1

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