c++ - 存储函数指针

Question

下面使用了一个简单的函数指针，但是如果我想存储那个函数指针怎么办？在那种情况下，变量声明会是什么样子？

#include <iostream>
#include <vector>

using namespace std;

double operation(double (*functocall)(double), double wsum);
double get_unipolar(double);
double get_bipolar(double);

int main()
{
    double k = operation(get_bipolar, 2); // how to store get_bipolar?
    cout << k;
    return 0;
}
double operation(double (*functocall)(double), double wsum)
{
    double g = (*functocall)(wsum);
    return g;
}
double get_unipolar(double wsum)
{
    double threshold = 3;
    if (wsum > threshold)
        return threshold;
    else
        return threshold;
}
double get_bipolar(double wsum)
{
    double threshold = 4;
    if (wsum > threshold)
        return threshold;
    else
        return threshold;
}

Answer 1

你的代码已经差不多完成了，你只是调用它似乎不正确，应该很简单

double operation(double (*functocall)(double), double wsum)
{
    double g;
    g = functocall(wsum);
    return g;
}

如果你想有一个变量，用同样的方式声明它

double (*functocall2)(double) = get_bipolar;

或已声明时

functocall2 = get_bipolar;

为您提供一个名为 functocall2 的变量，它引用 get_bipolar，通过简单的操作来调用它

functocall2(mydouble);

或通过

将其传递给操作

operation(functocall2, wsum);