存储函数指针

Question

下面使用一个简单的函数指针,但如果我想存储该函数指针怎么办？在这种情况下,变量声明会是什么样的？

#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

您的代码几乎已经完成,您似乎只是称之为不正确,它应该是简单的

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

如果你想要一个变量,它的声明方式是相同的

double (*functocall2)(double) = get_bipolar;

或者已经宣布

functocall2 = get_bipolar;

给你一个名为functocall2get_bipolar 的变量,通过简单的方式调用它

functocall2(mydouble);

或者将其传递给

operation(functocall2, wsum);

Answer 2

你已经(几乎)在你的代码中拥有它:

double (*functocall)(double) = &get_bipolar;

这定义了一个名为函数指针functocall指向get_bipolar.