函数指针的简单用法

#include <iostream>
using namespace std;


typedef double(*pFunc)(double &,double &);
double set_value(double &x,double &y)
{
cout<<"input height:";
cin>>x;
cout<<"input length:";
cin>>y;
return 0;
}


double t_area(double &x,double &y)
{
cout<<0.5*x*y<<endl;
return 0.5*x*y;
}


double s_area(double &x,double &y)
{
cout<<x*y<<endl;
return x*y;
}


double area(double &x,double &y,pFunc pf)
{
return pf(x,y);
}


int main()
{
double x,y;
//pFunc pf = NULL;
area(x,y,set_value);
area(x,y,t_area);
area(x,y,s_area);
return 1;
}