How to assign C++ vector to non-table global variable

Question

I'm trying to assign vector of floats to Lua's global variable.

First of all, my code works fine when I assign the vector to a variable which is already typed table.

However, it crashes when I assign the vector to variable which is non-table. (e.g. nil, number, string)

Here's my code.

  // get global table
  lua_getglobal(L, "mytab");

 // if it is table, clear table
 if(lua_istable(L, -1)) {
    lua_pushvalue(L, -1);
    lua_pushnil(L);

    while (lua_next(L, -2)) {
        lua_pop(L, 1);
        lua_pushvalue(L, -1);
        lua_pushnil(L);
        lua_settable(L, -4);
    }
    lua_pop(L, 1);
  }
  // set table
  vector<float> vec = {1,2,3,4,5};
  for (int i=0; i<vec.size(); ++i) {
      lua_pushinteger(L, i+1);
      lua_pushnumber(L, vec[i]);
      lua_settable(L, -3);
   }
   lua_pop(L, 1);

Calling this in Lua causes crash if the global variable mytab is set to nil, number or string.

How can I fix this? Thank you!

Answer 1

You seem to want to set to a new table to the global variable mytab. So, just forget the first part and do it:

  // set table
  lua_newtable(L);
  vector<float> vec = {1,2,3,4,5};
  for (int i=0; i<vec.size(); ++i) {
      lua_pushinteger(L, i+1);
      lua_pushnumber(L, vec[i]);
      lua_settable(L, -3);
   }
  lua_setglobal(L, "mytab");