Lua学习笔记

学习材料：https://www.runoob.com/lua/lua-tutorial.html

开发环境：SciTE

学习目标：学会使用Lua语法，并在C++中调用

学习时长：预计两天掌握

Lua基本语法

• --单行注释，--[[  code ]]--   
• 多行注释推荐使用 --[=[注释内容]=]，这样可以避免遇到table[table[idx]]时就将多行注释结束’

Lua数据类型

nil

• 一个未定义的变量，输出为nil
• 对于全局变量和table，nil可以起到删除的作用

  tab1 = {key1  = "val1",key2 ="val2","val3"}
  for k,v in pairs(tab1) do
  	print(k .. "-" .. v)
  end
  
  tab1.key1 =nil;
  for k,v in pairs(tab1) do
  	print(k .. "-" .. v)
  end
  

• 变量类型与nil作比较需要这样写：print(type(x) =="nil")

boolean

• Lua中，nil和false都可以认为是假

number

• 平时看到的数字都是

string

• [[   ]]中间可以加很多行，并且输出会保留空格和回车
• print("2" + "6") 是8
• “a” .. "b"  可以得到"ab"

table

• table = vector + map ，并且下标从1开始
• table在求长度的时候要用泛型for循环，tb[1],tb[2],tb[4] #tb=2

function

• 当作函数指针用就好啦

thread

• 线程和协程的区别：线程可以同一时刻有多个在运行，而协程任意一个时刻只能有一个在运行

userdate

• 程序员自定义的结构体和指针（没实践过）

Lua变量

• 默认都是全局，除非用local指定是局部变量
• a,b=b,a  (等价于swap(a,b))
• 应该尽可能使用局部变量，原因不用多说

Lua循环

for

• 数值FOR  :   for var =st,ed,delta
• 泛型FOR  :   for i,v in pairs(tableA) do   print()  end

Lua函数

• local function fuction_name(arg1,arg2,arg3) do ... end
• ...代表可变数组长度

  function average(...)
     result = 0
     local arg={...}
     for i,v in ipairs(arg) do
        result = result + v
     end
     print("总共传入 " .. select("#",...) .. " 个数")
     return result/select("#",...)
  end
  
  print("平均值为",average(10,5,3,4,5,6))

• 获取可变数组的总长度，第n个

• do
      function foo(...)
          for i = 1, select('#', ...) do  -->获取参数总数
              local arg = select(i, ...); -->读取参数
              print("arg", arg);
          end
      end
  
      foo(nil,nil);
  end
  

原表

• 简单的理解：对于一个表如果找不到要的数据，就找另一个表

VisualStudio中调用Lua

• C/C++：项目属性→常规→附加包含目录Include
• 链接器：常规→附加库目录lib文件夹
• 链接器：输入→附加依赖项lua5.1.lib lua51.lib

//用Lua编译器编译
extern "C" {
#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"
}
#include <cstring>
int main()
{
	lua_State* L = lua_open();
	luaopen_base(L);
	//luaL_loadfile(L, "C:/Users/76422/Desktop/testjob.lua");
	char ch[256] = "print(996)";
	luaL_loadbuffer(L, ch, strlen(ch), "haha");
	lua_pcall(L, 0, 0, 0);

	lua_close(L);
}

//获取Lua中的全局变量
extern "C" {
#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"
}
#include <cstring>
#include<stdio.h>
int main()
{
	lua_State* L = lua_open();
	luaopen_base(L);

	//luaL_loadfile(L, "C:/Users/76422/Desktop/testjob.lua");
	//lua_pcall(L, 0, 0, 0); 
	luaL_dofile(L, "C:/Users/76422/Desktop/test.lua");
	lua_getglobal(L, "a");
	int a = lua_tonumber(L, -1);
	printf("a=%d\n",a);

	lua_close(L);
}

//执行Lua脚本中的函数
extern "C" {
#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"
}
#include <cstring>
#include<stdio.h>
int main()
{
	lua_State* L = lua_open();
	luaopen_base(L);

	//luaL_loadfile(L, "C:/Users/76422/Desktop/testjob.lua");
	//lua_pcall(L, 0, 0, 0); 
	luaL_dofile(L, "C:/Users/76422/Desktop/test.lua");
	lua_getglobal(L, "get");
	lua_pushnumber(L,996);
	lua_pcall(L,1,1,0);
	int x = lua_tonumber(L, -1);
	

	lua_close(L);
}

//获取Lua脚本中Table的某个内容，每次gettable会把table也清空，因此取完一次后，要再执行lua_getglobal(L, "window") 一次
extern "C" {
#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"
}
#include <cstring>
#include<stdio.h>

int getValue(lua_State* L, const char* c) {
	lua_getglobal(L, "window");
	lua_pushstring(L, c);
	lua_gettable(L, -2);
	int res = lua_tonumber(L, -1);
	lua_pop(L, -1);
	printf("cnt = %d  res = %d\n",lua_gettop(L),res);
	return res;
}

int main()
{
	lua_State* L = lua_open();
	luaopen_base(L);

	//luaL_loadfile(L, "C:/Users/76422/Desktop/testjob.lua");
	//lua_pcall(L, 0, 0, 0); 
	luaL_dofile(L, "C:/Users/76422/Desktop/test.lua");
	lua_settop(L, 0);
	int wide = getValue(L, "wide");
	int height = getValue(L,"hight");

	lua_close(L);
}

C调用Lua(C)到此，基本上已经学会了如何使用，下一节是学习如果在Lua中调用C

在Lua中调用C

//
extern "C" {
#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"
}
#include <cstring>
#include<stdio.h>

int getValue(lua_State* L, const char* c) {
	lua_getglobal(L, "window");
	lua_pushstring(L, c);
	lua_gettable(L, -2);
	int res = lua_tonumber(L, -1);
	lua_pop(L, -1);
	printf("cnt = %d  res = %d\n",lua_gettop(L),res);
	return res;
}

int main()
{
	lua_State* L = lua_open();
	luaopen_base(L);

	//luaL_loadfile(L, "C:/Users/76422/Desktop/testjob.lua");
	//lua_pcall(L, 0, 0, 0); 
	int x = 30;
	lua_pushnumber(L, x);
	lua_setglobal(L, "x");
	luaL_dofile(L, "C:/Users/76422/Desktop/test.lua");
	//lua_settop(L, 0);
	//int wide = getValue(L, "wide");
	//int height = getValue(L,"hight");

	lua_close(L);
}

extern "C" {
#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"
}
#include <cstring>
#include<stdio.h>

int getValue(lua_State* L, const char* c) {
	lua_getglobal(L, "window");
	lua_pushstring(L, c);
	lua_gettable(L, -2);
	int res = lua_tonumber(L, -1);
	lua_pop(L, -1);
	printf("cnt = %d  res = %d\n",lua_gettop(L),res);
	return res;
}
//table全局变量
int main()
{
	lua_State* L = lua_open();
	luaopen_base(L);

	//luaL_loadfile(L, "C:/Users/76422/Desktop/testjob.lua");
	//lua_pcall(L, 0, 0, 0); 
	lua_settop(L, 0);
	int wide = 22333;
	int height = 2;
	lua_newtable(L);
	lua_pushstring(L, "width");
	lua_pushnumber(L, wide);
	lua_settable(L, -3);
	printf("cnt = %d \n", lua_gettop(L));
	lua_pushstring(L, "height");
	lua_pushnumber(L, height);
	lua_settable(L, -3);
	printf("222cnt = %d \n", lua_gettop(L));
	lua_setglobal(L,"t1");
	luaL_dofile(L, "C:/Users/76422/Desktop/test.lua");

	//int wide = getValue(L, "wide");
	//int height = getValue(L,"hight");

	lua_close(L);
}

//Lua调用C++函数
extern "C" {
#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"
}
#include <cstring>
#include<stdio.h>
int wide = 996;
int getValue(lua_State* L) {
	lua_pushnumber(L, wide);
	lua_pushnumber(L, 88);
	return 2;
}

int main()
{
	lua_State* L = lua_open();
	luaopen_base(L);

	//luaL_loadfile(L, "C:/Users/76422/Desktop/testjob.lua");
	//lua_pcall(L, 0, 0, 0); 
	lua_settop(L, 0);
	lua_pushcfunction(L, getValue);
	lua_setglobal(L,"eee");
	luaL_dofile(L, "C:/Users/76422/Desktop/test.lua");

	//int wide = getValue(L, "wide");
	//int height = getValue(L,"hight");

	lua_close(L);
}

//只会传一个，传2个有问题，问题暂留
extern "C" {
#include "lua.h"
#include "lauxlib.h"
#include "lualib.h"
}
#include <cstring>
#include<stdio.h>
int wide = 996;
int getValue(lua_State* L) {
	int sz = lua_tonumber(L, -1);
	lua_pop(L,-1);
	lua_pushnumber(L, wide *sz);
	lua_pushnumber(L, 88 *sz);
	return 2;
}

int main()
{
	lua_State* L = lua_open();
	luaopen_base(L);

	//luaL_loadfile(L, "C:/Users/76422/Desktop/testjob.lua");
	//lua_pcall(L, 0, 0, 0); 
	lua_settop(L, 0);
	lua_pushcfunction(L, getValue);
	lua_setglobal(L,"eee");
	luaL_dofile(L, "C:/Users/76422/Desktop/test.lua");

	//int wide = getValue(L, "wide");
	//int height = getValue(L,"hight");

	lua_close(L);
}