函数原型和函数调用

#include<iostream>
void cheers(int);//no return a value
double cube(double x);//return a double
int main()
{
	using namespace std;
	cheers(5);//函数调用 
	cout<<"Give me a number: ";
	double side;
	cin>>side;
	double volume = cube(side);//函数调用 
	cout<<"A "<<side<<"-foot cube has a volume of ";
	cout<<volume<<" cubic feet.\n";
	cheers(cube(2));
	return 0;

}
void cheers(int n )
{
	using namespace std;
	for(int i=0;i<n;i++)
	cout<<"Cheers ";
	cout<<endl;
}
double cube(double x)
{
	return x * x * x;
}