C++基础-函数指针

函数指针，顾名思义就是指向函数的指针，用一个变量来存储函数的地址，可以通过这个变量（指针）间接访问函数。（可以把函数指针名看作函数名来进行函数调用）。代码及说明如下：

#include <iostream>
#include<functional>

using namespace std;

class Test
{
public:
    int mul(int, int);
};

int Test::mul(int a, int b) 
{
    return a * b;
}

int add(int num1, int num2)
{
    int sum = num1 + num2;
    return  sum;
}

int sub(int num1, int num2)
{
    return num1 - num2;
}

int calc(int num1, int num2, int(*func)(int, int)) 
{
    return func(num1, num2);
}
int main()
{
    //1、获取函数地址与获取函数值
    cout << add << endl;    //00007FF7288B1465
    cout << sub << endl;   //00007FF7BDC51474
    cout << add(4, 5) << endl;  //9

    //2、使用函数指针
    //语法：返回类型 (*指针名称)(参数列表);
    cout << "*****************2" << endl;
    int (*fp1)(int, int) = add;
    cout << (*fp1)(2, 3) << endl;   //5
    cout << fp1(2, 3) << endl;  //5

    //3.使用typedef简化函数指针
    cout << "*****************3" << endl;
    typedef int(*Fp)(int, int);
    Fp fp2 = add;
    cout << fp2(6, 9) << endl;  //15

    //4.函数指针作为参数，将要执行的函数地址传过去
    cout << "*****************4" << endl;
    cout << calc(8, 2, add) << endl;    //10
    cout << calc(8, 2, sub) << endl;    //2

    //5.用functiona包装函数
    cout << "*****************5" << endl;
    function<int(int, int)> fp3 = add;
    cout << fp3(1, 2) << endl;  //3

    //6.数组函数指针
    cout << "*****************6" << endl;

    int(*fps[])(int, int) = { add, sub };
    for (auto fp : fps)
        cout << fp(4, 2) << endl;   //6   2

    function<int(int, int)> fps2[] = { add, sub };
    for (auto fp : fps2) 
        cout << fp(2, 1) << endl;   //3     1

    //7.类的成员函数指针
    cout << "*****************7" << endl;
    int(Test:: * fp4)(int, int) = &Test::mul;
    Test test;
    cout << (test.*fp4)(3, 4) << endl;  //12

}

输出结果：

00007FF701C9142E
00007FF701C910FA
9
*****************2
5
5
*****************3
15
*****************4
10
6
*****************5
3
*****************6
6
2
3
1
*****************7
12