Write function prototypes for the following:

- A function which receives an int and a float and returns a double.
double fun(int, float);

- A function that receives as int pointer and float reference and returns an int pointer.
int* fun (int *, float &);

- A function which doesn't receive anything and doesn't return anything. 
void fun();

- A function that receives an array of ints, and a float reference and doesn't return anything.
void fun(int *, float &);