C primer ++ 学习笔记第7篇——指针函数2

#include<iostream>
const double *f1(const double ar[],int n);
const double *f2(const double [],int);
const double *f3(const double *,int );

int main(){
	
	using namespace std;
	double av[3]={
		1111.3,2222.4,3333.5
	};
	
	const double *(*p1)(const double *,int )=f1;
	//auto随机定义类型，只可以单值初始化，不能初始化列表 
	//  auto p2=f2  等同于 
	const double *(*p2)(const double *,int )=f2;
	
	cout<<"using pointers to functions: \n" ;
	cout << "address valus \n ";
	cout << (*p1)(av ,3) <<":" << *(*p1)(av ,3) <<endl;
	cout << p2(av ,3) <<":" << *p2(av ,3) <<endl;
	
	
	const double *(*pa[3])(const double *,int )={
		f1,f2,f3
	};
	//auto pb=pa;
	const double *(**pb)(const double *,int )=pa;
	cout <<"\n using an array of pointers to functions:\n";
	cout << "address   value \n";
	for(int i=0;i<3;i++){
		
		cout << pa[i](av,3) <<":"<<  *pa[i](av,3)<<endl;
	}
	
	
	cout <<"\n using a pointer to a pointer to functions:\n";
	cout << "address   value \n";
	for(int i=0;i<3;i++){
		
		cout << pb[i](av,3) <<":"<<  *pb[i](av,3)<<endl;
	}
	
	
	cout << "\n using pointers to an array of pointers:\n";
	cout << "address     value \n";
	//auto pc=&pa;与下面等价 
	const double *(*(*pc)[3])(const double *,int )=&pa;
	cout << (*pc )[0](av,3)<<": "<< *(*pc)[0](av,3)<<endl;
	
	const double *(*(*pd)[3])(const double *,int )=&pa;
	const double *pdb =(*pd)[1](av,3);
	cout << pdb <<": " << *pdb <<endl;
	cout <<(*(*pd)[2])(av,3)<< ": " <<  *(*(*pd)[2])(av,3)<<endl;
	return 0;
	
}

const double *f1(const double *ar ,int n){
	return ar;
}

const double *f2(const double ar[] ,int n){
	return ar+1;
}

const double *f3(const double ar[],int n){
	return ar+2;
}

<img src="https://img-blog.youkuaiyun.com/20140606160310859?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvY29vbF9lYXN5/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/SouthEast" alt="" />

函数指针基础知识

//申明一个函数think 
int think(){
return 0； 
}
process(think); 
//think就是函数think()的地址 ，将函数think()的地址传送到process（） 
thought(think()); 
//将think()的返回值传送到thought() 


申明函数指针 
double pam(int );      //申明一个函数pam 
double  (*pf)(int);    //pf指针返回一个double数值 
double *pff (int);     //pff()返回一个double类型的指针 
pf = pam;              //初始化pf指针，让pf实现pam功能


const double * f1(const double ar[] , int n);
const double * f2(const double [] , int n);
const double * f3(const double * , int n);
//参数列表 const double ar[]与const double *ar的含义完全相同
// const double ar[]可以简化为 const double [] 
//const double *ar 可以简化为 const double * 
*pd[3]      //三个指针的指针数组 
(*pd)[3]    //一个指针指向三个元素的数组