Lua调用C++动态链接库.so

c++代码// testlib.cpp

#include <iostream>
#include <lua.hpp>
using namespace std;

/* 定义C++的Average 函数 */
int average(lua_State *L)
{
    int num = lua_gettop(L);  //获取参数个数

    double sum = 0;
    double avg = 0;

    for(int i = 1; i <= num; i++)   //注意Lua栈下标从1开始
    {
        sum += lua_tonumber(L, i);  //求和
    }

    avg = sum / num;   //求平均

    lua_pushnumber(L, avg);  //平均值入栈

    lua_pushnumber(L, sum);  //和入栈

    int size = lua_gettop(L);
    for(int i=1;i<=size;i++)
    {
        printf("[%d] = %f
",i, lua_tonumber(L, i));
    }

    return 2;   //return 返回值个数
}

/* 定义C++的sub函数 */
int sub(lua_State *L)
{
    int num = lua_gettop(L);
    if(num != 2)
    {
        cout << "Input param number is not correct!" << endl;
        return 0;
    }

    int a = lua_tonumber(L, 1);   //获取第一个参数，被减数
    int b = lua_tonumber(L, 2);   //获取第二个参数，减数

    int diff = a - b;
    lua_pushnumber(L, diff);   //结果压入栈

    return 1;
}

/* 定义C++的add函数 */
int add(lua_State *L)
{
    int num = lua_gettop(L);
    if(num != 2)
    {
        cout << "Input param number is not correct!" << endl;
        return 0;
    }

    int a = lua_tonumber(L, 1);   //获取第一个参数，被减数
    int b = lua_tonumber(L, 2);   //获取第二个参数，减数

    int sum = a + b;
    lua_pushnumber(L, sum);   //结果压入栈

    return 1;
}

//使用luaL_Reg注册新的C函数到Lua中
static const luaL_Reg test_functions[] =
        {
                {"average", average},
                {"add", add},
                {"sub", sub},
                {NULL, NULL}   //数组中最后一对必须是{NULL, NULL}，用来表示结束
        };


/* luaopen_XXX，XXX为库名称，若库名称为testlib.so，XXX即为testlib */
//luaopen_testlib函数前要加上 extern "C" 导出函数名才能被lua调用
//要不然在lua require的时候会报错找不到luaopen_testlib
extern "C" int luaopen_testlib(lua_State *L)
{
    luaL_newlib(L, test_functions);  //Lua 5.2之后用luaL_newlib代替了luaL_register
    return 1;
}

makefile

testlib.so: testlib.h testlib.cpp
	g++ -std=c++11 -shared -fPIC testlib.cpp -o testlib.so -I /usr/local/include/lua -l lua -l dl
clean:
	rm -f testlib.so

注：

-I /usr/local/include/lua     --->　　 指明要链接的lua头文件的路径
-l lua -l dl.   参考https://www.cnblogs.com/cy163/archive/2009/03/12/1409434.html，https://blog.csdn.net/qq_32534441/article/details/90552130?spm=1035.2023.3001.6557&utm_medium=distribute.pc_relevant_bbs_down.none-task-blog-2~all~first_rank_ecpm_v1~rank_v31_ecpm-1.nonecase&depth_1-utm_source=distribute.pc_relevant_bbs_down.none-task-blog-2~all~first_rank_ecpm_v1~rank_v31_ecpm-1.nonecase

在执行make命令之前需要利用lua源码编译出静态库(.a)或者动态库(.so)放在同级目录下，
要不然在执行make编译testlib.so时会报很多lua接口函数找不到

 

lua调用

local abc = require("testlib")
 
avg,sum = abc.average(100, 200, 300, 400, 500)
diff = abc.sub(100,50)
total = abc.add(100,50)
 
print("avg = ",avg)
print("sum =",sum)
print("diff = ",diff)
print("total = ",total)