C++函数指针详解

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doublecal(int);// prototype

double(*pf)(int);// 指针pf指向的函数， 输入参数为int,返回值为double

pf = cal;// 指针赋值

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voidestimate(intlines,double(*pf)(int));// 函数指针作为参数传递

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doubley = cal(5);// 通过函数调用

doubley = (*pf)(5);// 通过指针调用 推荐的写法

doubley = pf(5);// 这样也对， 但是不推荐这样写

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#include <iostream>

#include <algorithm>

#include <cmath>

usingnamespacestd;

doublecal_m1(intlines)

{

return0.05 * lines;

}

doublecal_m2(intlines)

{

return0.5 * lines;

}

voidestimate(intline_num,double(*pf)(intlines))

{

cout <<"The "<< line_num <<" need time is: "<< (*pf)(line_num) << endl;

}

intmain(intargc,char*argv[])

{

intline_num = 10;

// 函数名就是指针，直接传入函数名

estimate(line_num, cal_m1);

estimate(line_num, cal_m2);

return0;

}

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#include <iostream>

#include <algorithm>

#include <cmath>

usingnamespacestd;

// prototype 实质上三个函数的参数列表是等价的

constdouble* f1(constdoublearr[],intn);

constdouble* f2(constdouble[],int);

constdouble* f3(constdouble* ,int);

intmain(intargc,char*argv[])

{

doublea[3] = {12.1, 3.4, 4.5};

// 声明指针

constdouble* (*p1)(constdouble*,int) = f1;

cout <<"Pointer 1 : "<< p1(a, 3) <<" : "<< *(p1(a, 3)) << endl;

cout <<"Pointer 1 : "<< (*p1)(a, 3) <<" : "<< *((*p1)(a, 3)) << endl;

constdouble* (*parray[3])(constdouble*,int) = {f1, f2, f3};// 声明一个指针数组，存储三个函数的地址

cout <<"Pointer array : "<< parray[2](a, 3) <<" : "<< *(parray[2](a, 3)) << endl;

cout <<"Pointer array : "<< parray[2](a, 3) <<" : "<< *(parray[2](a, 3)) << endl;

cout <<"Pointer array : "<< (*parray[2])(a, 3) <<" : "<< *((*parray[2])(a, 3)) << endl;

return0;

}

constdouble* f1(constdoublearr[],intn)

{

returnarr;// 首地址

}

constdouble* f2(constdoublearr[],intn)

{

returnarr+1;

}

constdouble* f3(constdouble* arr,intn)

{

returnarr+2;

}

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typedefconstdouble* (*pf)(constdouble[],int);// 将pf定义为一个类型名称；

pf p1 = f1;

pf p2 = f2;

pf p3 = f3;