load and execute lua function

make.sh

g++ -o test test.cpp -llua

test.cpp

#include <iostream>
#include <lua.hpp>

using namespace std;

int main(int argc, char **argv)
{
    if (argc != 2) {
        cout << "test: usage: test <filename>" << endl;
        return 0;
    }

    const char *file = argv[1];
    lua_State *L = lua_open();
    luaL_openlibs(L);

    cout << "Loading file " << file << endl;

    int s;
    if((s = (luaL_loadfile(L, file) || lua_pcall(L, 0, 0, 0)))) {
        cout << "Error: " << lua_tostring(L, -1);
    }

    if (s == 0) {
        // make the call
        lua_getglobal(L, "test");
        lua_pushinteger(L, 4);
        s = lua_pcall(L, 1, 0, 0);
        if (s) cout << "Error: " << lua_tostring(L, -1);
    }

    lua_close(L);

    return 0;
}

test.lua

function test (x)
    if x == 1 then
        io.write("hello");
    else
        io.write("not a one");
    end
end