[solved]using lua with c++

[cndr]

I am new to lua, and I would like to make lua change variables in c++, say I have something like the following code, the hardest thing I have learning lua, is integrating it into c++.

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extern "C"
{
#include "lua.h"
#include "lualib.h"
#include "lauxlib.h"
}
int main()
{
 int s = 0;
int x;
lua_State *L = lua_open();
luaL_openlibs(L);
luaL_dofile(L,"file.lua"); // lua would set x to 5
printf("x is %d .",x); //how would I get lua to set x?
lua_close(L);
return 0;
}

[mv2112]

There are a few ways you could do this but here i think is the easiest.

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    extern "C"
    {
    #include "lua.h"
    #include "lualib.h"
    #include "lauxlib.h"
    }
    int main()
    {
    int s = 0;
    int x;
    lua_State *L = lua_open();
    luaL_openlibs(L);
    luaL_dofile(L,"file.lua"); // lua would set x to 5
    x=lua_getglobal(L,"x"); //assuming the variable in the lua script is also named x 
    printf("x is %d .",x); //how would I get lua to set x?
    lua_close(L);
    return 0;
    }

You could also register a SetX function to lua but X would have to be global.

[cndr]

didn't work for me, maybe I should just stick with pure lua for a while, it seems getting the code to work with c++ is harder than I thought, when I ran the code I got the following error message:

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error: void value not ignored as it ought to be

the lua file just had

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x =5;

[mv2112]

Oops, my code was wrong, this works, i tested it:

Code: Select all

        extern "C"
        {
        #include "lua.h"
        #include "lualib.h"
        #include "lauxlib.h"
        }
        int main()
        {
        int s = 0;
        int x;
        lua_State *L = lua_open();
        luaL_openlibs(L);
        luaL_dofile(L,"file.lua"); // lua would set x to 5
        lua_getglobal(L,"x"); //assuming the variable in the lua script is also named x
	x=lua_tonumber(L,-1); //gets x from the lua stack
        printf("x is %d .",x); 
        lua_close(L);
        return 0;
        }

[cndr]

Thanks for the help I really appreciate it