c++ - 函数指针类型是什么意思？

Question

我的类作业是这样写的:

Write a declaration for a function that takes two int parameters and returns an int, and declare a vector whose elements have this function pointer type.

既然函数和 vector 都是 int，这是否正确？我对指针仍然很模糊。这是我的:

#include <iostream>
#include <vector>
using std::cin; using std::cout; using std::endl; using std::vector;

// This is my function that take two ints and returns and int
int AddFunc ( int a, int b) { int addResult; addResult = a + b; return (addResult);}

int main()
{
    vector <int> v1; // Declare a vector whose elements have this functions pointer types
    int add1, add2, add3 = 0;
        cout << "Enter two numbers to be added with my AddFunc function: ";
        cin >> add1 >> add2;
        add3 = AddFunc (add1, add2);
        cout << "The numbers added equal: " << add3 << endl;
        v1.push_back(add3);
        cout << "The first element in the vector v1 is: " << v1 [0] << endl;
    return 0;
}

Answer 1

函数指针类型为int (*)(int, int)。你想要这个:

typedef int (*fptr)(int, int);

std::vector<fptr> v;

例子:

int add(int a, int b) { return a + b; }
int mul(int a, int b) { return a * b; }

v.push_back(&add);
v.push_back(&mul);

然后是这样的:

for (f : v) { std::cout << "f(5, 7) = " << f(5, 7) << std::endl; }