多个函数使用函数指针

#include <iostream>


using namespace std;


double calculate(double x, double y, double (*pf)(double, double));  // 函数指针


double add(double x, double y);    //加法函数
double sub(double x, double y);    //减法函数
double mean(double x, double y);    //平均函数




int main()
{
    
double a, b;


double (*pf[3])(double, double) = {add, sub, mean};  // 多个函数指针的使用
char * op[3] = {"add", "sub", "mean"};


cout << "Enter pairs of numbers (q to quit): ";
while (cin >> a >> b)
{
for (int i=0; i<3; i++)
{
cout << op[i] << ": " << a << " and " << b << " = "
<< calculate(a, b, pf[i]) << endl;


}
}
}




double calculate(double x, double y, double (*pf)(double, double))
{
return (*pf)(x, y);   //具体的返回值
 }




double add(double x, double y)
{
return x + y;
}




double sub(double x, double y)
{
return x - y;
}




double mean(double x, double y)
{
return (x + y) / 2.0;
}