lua_newuserdata简单使用

来源：互联网发布：信贷规模数据编辑：程序博客网时间：2024/06/05 00:25

void *lua_newuserdata (lua_State *L, size_t size);

lua_newuserdata 函数按照指定的大小分配一块内存，将对应的 userdatum放到栈内，
并返回内存块的地址。

一个简单的调用lua_newuserdata 分配空间的例子：

LuaTestDll.h

extern "C"{#include "lua/lua.h"#include "lua/lualib.h"#include "lua/lauxlib.h"#include "lua/luaconf.h"LUATESTDLL_API int luaopen_mylib(lua_State *L);};

LuaTestDll.cpp

#include "LuaTestDll.h"typedef struct NumArray{int size;double values[1];}NumArray;static int newarray(lua_State *L){int n = luaL_checkint(L,1);//由于原始的结构中已经包含了一个元素的空间，所以我们从n 中减去 1size_t nbytes = sizeof(NumArray) + (n-1)*sizeof(double);//调用lua_newuserdata分配指定的大小空间，并压入栈中作为返回值NumArray *a = (NumArray*)lua_newuserdata(L,nbytes);a->size = n;//分配的内存已经在栈中return 1;}static int setarray(lua_State *L){NumArray *a = (NumArray*)lua_touserdata(L,1);int index = luaL_checkint(L,2);double value = luaL_checknumber(L,3);luaL_argcheck(L,a != NULL,1,"array expected");luaL_argcheck(L,1<=index && index <=a->size,2,"index out of range");//设置数组值a->values[index-1] = value;return 0;}static int getarray (lua_State *L){NumArray *a = (NumArray*)lua_touserdata(L,1);int index = luaL_checkint(L,2);luaL_argcheck(L,a != NULL,1,"array expected");luaL_argcheck(L,1<=index && index <=a->size,2,"index out of range");//返回对应值lua_pushnumber(L,a->values[index-1]);return 1;}static int getsize(lua_State *L){NumArray *a = (NumArray*)lua_touserdata(L,1);//判断参数正确性luaL_argcheck(L,a != NULL,1,"array expected");//返回数组大小lua_pushnumber(L,a->size);return 1;}static const struct luaL_reg arraylib[] = {{"new",newarray},{"set",setarray},{"get",getarray},{"size",getsize},{NULL,NULL}};int luaopen_mylib(lua_State *L){luaL_openlib(L,"array",arraylib,0);return 1;}

Test.lua

func =  package.loadlib("LuaTestDll.dll","luaopen_mylib");func();--导出函数a = array.new(1000);--分配1000个空间大小print(a);--> userdata: 0x8064d48 print(array.size(a));--> 1000for i=1,1000 doarray.set(a,i,1/i);endprint(array.get(a,10));--> 0.1

0 0