C++primer plus第六版课后编程题答案7.10

#include <iostream>
using namespace std;
double add(double a,double b){return a+b;};//为了简化，这三个函数我直接在这里写了。
double dev(double a,double b){return a-b;};
double mul(double a,double b){return a*b;};
double calculate(double a,double b,double (*pf[])(double x,double y));
void main710()
{
double (*pf[3])(double,double)={add,dev,mul};
double result=calculate(2.5,4.0,pf);
cout<<"\nresult="<<result;
system("pause");

}
double calculate(double a,double b,double (*pf[])(double x,double y))
{
int size=sizeof(pf);//获取里面有多少个函数
cout<<"size="<<size<<endl;//测试到size=4,可能是最后一个‘\0’
cout<<"The result of "<<a<<" and b:"<<endl;//这里少了个<<b，请自行加上去----2015.01.20
double sum=0;
for(int i=0;i<size-1;i++)
{
//cout<<"now i="<<i<<endl;
//cout<<"The result of "<<a<<" and b:"<<endl;
cout<<pf[i](a,b)<<endl;
sum+=pf[i](a,b);
}

return sum;

}