#include "lua.h"
#include "lauxlib.h"
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>typedef struct NumArray
{int size;double values[1];
}NumArray;static int
lnew(lua_State *L)
{int arr_size = luaL_checkint(L, 1);if (arr_size <= 0){assert(NULL);}size_t nbytes = sizeof(NumArray) + (arr_size - 1) * sizeof(double);NumArray *na = (NumArray *)lua_newuserdata(L, nbytes);na->size = arr_size;return 1;
}static int
lset(lua_State *L)
{NumArray *na = (NumArray *)lua_touserdata(L, 1);int idx = luaL_checkint(L, 2);double value = luaL_checknumber(L, 3);printf("idx %d, value %f\n", idx, value);luaL_argcheck(L, na != NULL, 1, "array expected");luaL_argcheck(L, 1 <= idx && idx <= na->size , 2, "index out of range");na->values[idx - 1] = value;return 0;
}static int
lget(lua_State *L)
{NumArray *na = (NumArray *)lua_touserdata(L, 1);int idx = luaL_checkinteger(L, 2);luaL_argcheck(L, na != NULL, 1, "array expected");luaL_argcheck(L, 1 <= idx && idx <= na->size, 2, "index out of range");lua_pushnumber(L, na->values[idx - 1]);return 1;
}    static int
lfind(lua_State *L)
{NumArray *na = (NumArray *)lua_touserdata(L, 1);assert(na != NULL);double elem = luaL_checknumber(L, 2);int idx;for (idx = 0; idx < na->size; idx++){if (na->values[idx] == elem){lua_pushnumber(L, idx + 1);return 1;}}lua_pushnumber(L, -1);return 1;
}int
luaopen_newarray(lua_State *L)
{luaL_checkversion(L);luaL_Reg l[] = {{"new", lnew},{"set", lset},{"get", lget},{"find", lfind},{NULL, NULL},};luaL_newlib(L, l);return 1;
}

local newarray = require "newarray"print(newarray)
local na = newarray.new(1000)newarray.set(na, 1, 100)local value = newarray.find(na, 100)if value ~= -1 thenprint("value is ", value)
elseprint("not exists")
end