#include <iostream>
using namespace std;

struct myclass {
    myclass() : x(0) {}
    
    double x;
};

double testfunction ( double x , void *param ) {
    myclass *bar=static_cast<myclass*>(param);

    /*** do something with x and bar***/ 

    return bar->x;

}

int main() {
	// your code goes here
	
	
	return 0;
}