How to return an array as table from C function to lua?

Question

I need impelement a C function for lua script to call.I shall return an array as table from that function.I used the code blow but crashed.Could anyone tell me how to use it?

struct Point {
    int x, y;
}
typedef Point Point;


static int returnImageProxy(lua_State *L)
{
    Point points[3] = {{11, 12}, {21, 22}, {31, 32}};

    lua_newtable(L);

    for (int i = 0; i  3; i++) {
        lua_newtable(L);
        lua_pushnumber(L, points[i].x);
        lua_rawseti(L, -2, 2*i+1);
        lua_pushnumber(L, points[i].y);
        lua_rawseti(L, -2, 2*i+2);
        lua_settable(L,-3);
    }

    return 1;   // I want to return a Lua table like :{{11, 12}, {21, 22}, {31, 32}}
}

Answer 1

Need to change the lua_settable as @lhf mentions. Also, you are always adding into the first 2 indices of the sub-tables

typedef struct Point {
    int x, y;
} Point;


static int returnImageProxy(lua_State *L)
{
    Point points[3] = {{11, 12}, {21, 22}, {31, 32}};

    lua_newtable(L);

    for (int i = 0; i < 3; i++) {
        lua_newtable(L);
        lua_pushnumber(L, points[i].x);
        lua_rawseti(L, -2, 1);
        lua_pushnumber(L, points[i].y);
        lua_rawseti(L, -2, 2);

        lua_rawseti(L, -2, i+1);
    }

    return 1;   // I want to return a Lua table like :{{11, 12}, {21, 22}, {31, 32}}
}

Answer 2

Try replacing lua_settable(L,-3) with lua_rawseti(L,-2,i+1).