Linked from: http://www.faqs.org/docs/Linux-mini/C++-dlopen.html
//1.==== main.cpp =============================================================
// How to build?
// g++ main.cpp -ldl
//=============================================================================
#include "polygon.h"
#include <iostream>
#include <dlfcn.h>
int main() {
using std::cout;
using std::cerr;
// load the triangle library
void* triangle = dlopen("./triangle.so", RTLD_LAZY);
if (!triangle) {
cerr << "Cannot load library: " << dlerror() << '\n';
return 1;
}
// load the symbols
create_t* create_triangle = (create_t*) dlsym(triangle, "create");
destroy_t* destroy_triangle = (destroy_t*) dlsym(triangle, "destroy");
if (!create_triangle || !destroy_triangle) {
cerr << "Cannot load symbols: " << dlerror() << '\n';
return 1;
}
// create an instance of the class
polygon* poly = create_triangle();
// use the class
poly->set_side_length(7);
cout << "The area is: " << poly->area() << '\n';
// destroy the class
destroy_triangle(poly);
// unload the triangle library
dlclose(triangle);
}
//2.=====polygon.h======================================
#ifndef POLYGON_HPP
#define POLYGON_HPP
class polygon {
protected:
double side_length_;
public:
