Lua与C/C++的一些简单交互

我只写简单的！

• lua版本 5.1.4
• 环境 ubuntu 12.04

从C/C++调用lua中自定义的函数

#include <lua.hpp>
#include <iostream>
using namespace std;

int main(int argc, const char * argv[])
{
  lua_State *L = luaL_newstate();
  luaopen_base(L);
  luaL_openlibs(L);

  int ret = luaL_dofile(L, "test.lua");
  if (ret != 0)
    {
      cout << "load test.lua failed" << endl;
      return 1;
    }

  lua_getglobal(L, "showValue");
  lua_pushstring(L, "W");
  lua_pushstring(L, "HH");

  lua_pcall(L, 2, 0, 0);

  lua_close(L);

  return 0;c++
}

test.lua文件：

function showValue(strFirstName, strLastName)
	 print(strFirstName .. "." .. strLastName)
end

从lua中返回一个值给C/C++

main.cpp，注意lua_pcall中设置了返回3个值

#include <lua.hpp>
#include <iostream>
using namespace std;

int main(int argc, const char * argv[])
{
  lua_State *L = luaL_newstate();
  luaopen_base(L);
  luaL_openlibs(L);

  int ret = luaL_dofile(L, "test.lua");
  if (ret != 0)
    {
      cout << "load test.lua failed" << endl;
      return 1;
    }

  lua_getglobal(L, "showValue");
  lua_pushstring(L, "W");
  lua_pushstring(L, "HH");

  lua_pcall(L, 2, 3, 0);

  int nOld = lua_tonumber(L, -1);
  const char *pIs = lua_tostring(L, -2);
  const char *pName = lua_tostring(L, -3);

  cout << pName << " " << pIs << " " << nOld << endl;

  lua_pop(L, 3);

  lua_close(L);

  return 0;
}

test.lua文件返回了3个值

function showValue(strFirstName, strLastName)
	 strName = strFirstName .. "." .. strLastName
	 print(strName)
	 return strName, "is", 18
end

Lua调用C/C++中自定义的函数

Lua不能调用任意的C/C++函数。可以向Lua中注册的函数，需要符合以下的规范：
typedef int (*lua_CFunction) (lua_State *L);
main.cpp，定义了一个名为lua_printValue的函数，并且注册为PrintValue的lua函数，以便于在Lua中使用。

#include <lua.hpp>
#include <iostream>
using namespace std;

int lua_printValue(lua_State *L)
{
  // get the parameter
  const char *pValue = lua_tostring(L, -1);

  // do something here...

  lua_pushstring(L, pValue);
  lua_pushstring(L, "Year");

  // return 2 value
  return 2;
}

int main(int argc, const char * argv[])
{
  lua_State *L = luaL_newstate();
  luaopen_base(L);
  luaL_openlibs(L);

  // register the lua_printValue function
  // as PrintValue which can be used in lua
  lua_pushcfunction(L, lua_printValue);
  lua_setglobal(L, "PrintValue");

  int ret = luaL_dofile(L, "test.lua");
  if (ret != 0)
    {
      cout << "load test.lua failed" << endl;
      return 1;
    }

  lua_getglobal(L, "showValue");
  lua_pushstring(L, "W");
  lua_pushstring(L, "HH");

  lua_pcall(L, 2, 3, 0);

  int nOld = lua_tonumber(L, -1);
  const char *pIs = lua_tostring(L, -2);
  const char *pName = lua_tostring(L, -3);

  cout << pName << " " << pIs << " " << nOld << endl;

  lua_pop(L, 3);

  lua_close(L);

  return 0;
}

test.lua文件：

function showValue(strFirstName, strLastName)
	 strName = strFirstName .. "." .. strLastName
	 strThis, strYear = PrintValue("this")
	 strAge = strThis .. " " .. strYear .. " is"
	 return strName, strAge, 18
end

PrintValue从Lua中接受一个参数，在C/C++中处理了一下，返回两个参数给Lua。