Dynamically load and invoke a function in C++

gistfile1.hpp

///////////////////////////////////////////////////////////////////////////////
// dyn.cc - compiled and linked as a dynamic library
///////////////////////////////////////////////////////////////////////////////
#include <iostream>

extern "C" void fun()
{
    std::cout << "BOOYA!!1!  fun() invoked!\n";
}

///////////////////////////////////////////////////////////////////////////////
// play.cc - compiled and linked as a regular binary, separately from dyn.cc
///////////////////////////////////////////////////////////////////////////////
#include <iostream>
#include <dlfcn.h>

using namespace std;

int main(int argc, char* argv[])
{
    const char* const DYLIB = "libdyn.dylib" /* or .so or .dll or ... */
    const char* const SYM = "fun";

    cout << "Loading library " << DYLIB << " ..." << endl;
    void* handle = dlopen(DYLIB, RTLD_NOW);
    if( !handle ) {
        cerr << "Error loading library: " <<  dlerror() << endl;
        return -1;
    }
    cout << "Loading symbol " << SYM << " ..." << endl;
    dlerror(); // clear any error
    void* ret_sym = dlsym(handle, SYM);
    if( ! ret_sym ) {
        cerr << "Error loading symbol: " << dlerror() << endl;
        dlclose(handle);
        return -1;
    } else {
        typedef void (*fun_t)();
        fun_t fun = (fun_t)ret_sym;
        cout << "Calling " << SYM << "() ..." << endl;
        fun();
    }
    dlclose(handle);
    return 0;
}