C++primer plus 6th 第7章7.10编程答案

#include <iostream>
double calculate(double a,double b,double (*ptr)(double a,double b));
double add(double a,double b);
double div(double a,double b);
int main() {
    using namespace std;
    cout<<"Enter two double numbers:";
    double a,b;
    while(cin>>a>>b)
    {
        cout<<"Add is : "<<calculate(a,b,add)<<endl;
        cout<<"Divided is : "<<calculate(a,b,div)<<endl;;
        cout<<"Next pairs numbers:";
        
    }
    return 0;
}
double calculate(double a,double b,double (*ptr)(double a,double b))
{
    return ptr(a,b);
    
}
double add(double a,double b)
{
    return a+b;
}
double div(double a,double b)
{
    return a/b;
}