Lua 與 C 擴充 -透過 C++ 執行檔的各種處理

Lua 與 C 擴充 -透過 C++ 執行檔的各種處理

環境
windows 11 64bit
Visual Studio 2022
Lua 5.4.6

首先做好基本準備

main.cpp

#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
using namespace std;

#include <K:\Lua\546\lib17\include\lua.hpp>

#ifdef _WIN64
#ifdef _DEBUG
#pragma comment(lib,"K:\\Lua\\546\\lib17\\x64\\Debug\\lua54.lib")
#else
#pragma comment(lib,"K:\\Lua\\546\\lib17\\x64\\Release\\lua54.lib")
#endif
#else
#ifdef _DEBUG
#pragma comment(lib,"K:\\Lua\\546\\lib17\\x86\\Debug\\lua54.lib")
#else
#pragma comment(lib,"K:\\Lua\\546\\lib17\\x86\\Release\\lua54.lib")
#endif
#endif

lua_State* LuaOpen()
{
	lua_State* pLua = luaL_newstate();
	if (!pLua)
	{
		printf("Failed to open Lua\n");
		return 0;
	}

	luaL_openlibs(pLua);
	return pLua;
}

int main()
{
	//LuaTest01();	//單純執行 lua 檔
	//LuaTest02();	//傳去 lua 做加法
	//LuaTest03();	//Lua 呼叫 C++ Function
	//LuaTest04();	//Lua 呼叫 C++ Function

	system("pause");
	return 0;
}

1. 單純執行 lua 檔

void LuaTest01()	//單純執行 lua 檔
{
	// 開啟Lua
	lua_State* pLua = LuaOpen();
	if (!pLua)
		return;

	// 執行整個Lua檔
	luaL_dofile(pLua, "hello.lua");

	lua_close(pLua);
	return;
}

hello.lua

--hello.lua
print("Hello world! Hello Lua!")

執行結果

2. 傳去 lua 做加法

int add(lua_State *pLua, int x, int y)
{
	int result;

	lua_getglobal(pLua, "luaadd");
	lua_pushnumber(pLua, x);
	lua_pushnumber(pLua, y);

	lua_call(pLua, 2, 1);	// 2 個傳入值和 1 個回傳值

	result = lua_tointeger(pLua, -1); 
	/*上面這行code有個地方要注意, 
	就是第二個參數(index), index 1 and -n stand for the first element in the stack, 
	index n and -1 stand for the last element in the stack, 
	所以上面這行就是把最後放進去的data拿出來, 也就是要回傳的值*/

	lua_pop(pLua, 1); //pop returned value

	return result;
}
void LuaTest02()	//傳去 lua 做加法
{
	// 開啟Lua
	lua_State* pLua = LuaOpen();
	if (!pLua)
		return;

	luaL_dofile(pLua, "add.lua");

	//呼叫lua的函式
	int sum = add(pLua, 4, 3);
	printf("The sum is %d\n", sum);

	lua_close(pLua);
}

add.lua

function luaadd(x, y)
	return x+y
end

執行結果

3. Lua 呼叫 C++ Function

int SayHello(lua_State* pLua)
{
	const char* Name = lua_tostring(pLua, 1); // 取得堆疊底層第一個參數的Name
	char Hello[128] = "Hello! ";
	strcat_s(Hello, Name);
	lua_pushstring(pLua, Hello); // 推入回傳字串進堆疊
	return 1; // 告訴Lua我們有一個回傳值
}
void LuaTest03()	//Lua 呼叫 C++ Function
{
	// 開啟Lua
	lua_State* pLua = LuaOpen();
	if (!pLua)
		return;

	lua_register(pLua, "SayHello", SayHello);

	// 執行整個Lua檔
	luaL_dofile(pLua, "hello2.lua");

	lua_close(pLua);
}

hello2.lua

-- hello2.lua
print(SayHello("Charlie"))

執行結果

4. Lua 呼叫 C++ Function

int sum_and_minus(lua_State* pLua)
{
	//get the total number of arguments
	int num_args = lua_gettop(pLua);

	double sum = 0;
	double minus = 0;

	//index 1 indicates the first argument, index num_args indicates the last argument
	for (int i = 1; i <= num_args; i++)
		sum += lua_tonumber(pLua, i);

	//這裡的作法是0-3-5  所以是 -8
	for (int i = 1; i <= num_args; i++)
		minus -= lua_tonumber(pLua, i); //push the result into the stack

	lua_pushnumber(pLua, sum);
	lua_pushnumber(pLua, minus);

	return 2;	//return the total number of the results
}
void LuaTest04()	//Lua 呼叫 C++ Function
{
	lua_State* pLua = LuaOpen();
	if (!pLua)
		return;

	lua_register(pLua, "sum_and_minus", sum_and_minus);

	luaL_dofile(pLua, "func.lua");

	lua_close(pLua);
}

func.lua

sum,minus = sum_and_minus(3,5)

print("Sum = ", sum)
print("Minus = ", minus)

執行結果

回到目錄
https://husking-studio.com/extending-lua-with-c