Easy enough ,

Include conio.h and put a getch() before return 0; in main().getch() waits for the user to press a key and it returns that value.

So

So if the user pressed enter the int value is 13, if it is 'A' the int value is 64 i.e the ascii values of the key pressed.

Helps?

you could use a while loop or if your using m$ use cmd to open the exe

but any ways the while loop for ya

#include <iostream>
using namespace std;

double Cube (double Value);

main ()
{
char quit; //declare a char variable char
while (quit != 'q') //the while loop
{
double Number, CubeNumber;

cout << "Enter a number: ";
cin >> Number;

CubeNumber = Cube (Number);

cout << CubeNumber << endl;
cout << "\nPress q to quit\n";
cin>>quit; //when q is entered the program will exit
}
return 0;
}

double Cube (double Value)
{
double CubeReturn;

CubeReturn = Value * Value * Value;

return CubeReturn;
}

Think this is what your after but i would recomend using the cmd method intill you get used to loops and the way they work.

Well, you could just add this to the last line :
system("Pause") ;