Question

What I’m looking for is something like:

lua script

MY_ARRAY = {
00, 10, 54, 32,
12, 31, 55, 43,
34, 65, 76, 34,
53, 78, 34, 93
}

c code

lua_Number array[] = lua_getarray("MY_ARRAY");

Is this possible? Is there anything similar to make dealing with lua tables in C easier.

Answer 1

You can write such function yourself! It shouldn’t be too many lines. But it’s better to use pointers than arrays, because they can point to any number of elements. The interface could be something like this:

lua_Number *values;
size_t nvalues;
values = luaGetNumbers("MY_ARRAY", &nvalues);
/* the number of values is now nvalues */
for (int i=0; i<nvalues; i++) {
     /* do something with values[i] */
}
free(values);

And the implementation should use the following functions (from http://www.lua.org/manual/5.2/manual.html):

void lua_getglobal (lua_State *L, const char *name);

Pushes onto the stack the value of the global name.

---

void lua_gettable (lua_State *L, int index);

Pushes onto the stack the value t[k], where t is the value at the
given valid index and k is the value at the top of the stack.

This function pops the key from the stack putting the resulting value
in its place). As in Lua, this function may trigger a metamethod for
the “index” event (see §2.4).

---

lua_Number lua_tonumberx (lua_State *L, int index, int *isnum);

Converts the Lua value at the given acceptable index to the C type
lua_Number (see lua_Number). The Lua value must be a number or a
string convertible to a number (see §3.4.2); otherwise, lua_tonumberx
returns 0.

If isnum is not NULL, its referent is assigned a boolean value that
indicates whether the operation succeeded.

---

void lua_len (lua_State *L, int index);

Returns the “length” of the value at the given acceptable index; it is
equivalent to the ‘#’ operator in Lua (see §3.4.6). The result is
pushed on the stack.