C++primer plus第六版课后编程题答案7.10

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;
	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;

}