Iterating through a Lua table from C++?

Question

I\'m trying to load tables from Lua to C++ but I\'m having trouble getting it right. I\'m getting through the first iteration just fine but then at the second call to lua_ne

Answer 1

Reading LUA manual lua_next you find that problems may arise on using lua_tostring on a key directly, that is you have to check the value of the key and then decide to use lua_tostring or lua_tonumber. So you could try this code:

   std::string key
   while(lua_next(L, -2) != 0){ // in your case index may not be -2, check

    // uses 'key' (at index -2) and 'value' (at index -1)

    if (lua_type(L, -2)==LUA_TSTRING){ // check if key is a string
         // you may use key.assign(lua_tostring(L,-2));
    }
    else if (lua_type(L, -2)==LUA_TNUMBER){ //or if it is a number
         // this is likely to be your case since you table level = { 1, 2, 3, }
         // don't declare field ID's
         // try:
         // sprintf(buf,"%g",lua_tonumber(L,-2));
         // key.assign(buf);
    }
    else{
        // do some other stuff
    }
    key.clear();
    lua_pop(L,1)
   }

Hope it helps.