lua实践-lua里调用C函数

准备工作

# apt-get install lua5.1 liblua5.1-0-dev

因为想移植到LEDE/OpenWRT, 所以选择了 lua 5.1版本

上代码

#include "stdio.h"

#include "lua5.1/lauxlib.h"
#include "lua5.1/lualib.h"

static int add2(lua_State* L)
{
    double op1 = luaL_checknumber(L,1);
    double op2 = luaL_checknumber(L,2);

    lua_pushnumber(L,op1 + op2);
    return 1;
}

static int sub2(lua_State* L)
{
    double op1 = luaL_checknumber(L,1);
    double op2 = luaL_checknumber(L,2);
    
    lua_pushnumber(L,op1 - op2);
    return 1;
}

const char* testfunc = "print(add2(1.0,2.0)) print(sub2(20.1,19))"; 

int main()
{
    lua_State* L = luaL_newstate();
    luaL_openlibs(L);

    lua_register(L, "add2", add2);
    lua_register(L, "sub2", sub2);

    if (luaL_dostring(L,testfunc)) {
        printf("Failed to invoke.\n");
    }
	
    lua_close(L);
    return 0;
}

编译

gcc test.c -llua5.1 -o luatest

运行

./luatest
3
1.1

反过来， C做扩展库，让lua调用

#include "stdio.h"

#include "lua5.1/lauxlib.h"
#include "lua5.1/lualib.h"

static int add(lua_State* L) 
{
    double op1 = luaL_checknumber(L,1);
    double op2 = luaL_checknumber(L,2);
    lua_pushnumber(L,op1 + op2);
    return 1;
}

static int sub(lua_State* L)
{
    double op1 = luaL_checknumber(L,1);
    double op2 = luaL_checknumber(L,2);
    lua_pushnumber(L,op1 - op2);
    return 1;
}

static luaL_Reg mylibs[] = { 
    {"add", add},
    {"sub", sub},
    {NULL, NULL} 
};


int luaopen_mytestlib(lua_State* L) 
{
    const char* libName = "mytestlib";
    luaL_register(L, libName, mylibs);
    return 1;
}

编译成so库

gcc testlib.c -fPIC -shared -o mytestlib.so

test.lua

require "mytestlib"
 
print(mytestlib.add(1.0, 2.0))
print(mytestlib.sub(20.1, 19))

运行

lua test.lua
3
1.1