#include <iostream>
using namespace std;

int f (int x, int y) { return y-x; }

int main()
{
int a = 5, b = 6, f(int, int), (*g)(int, int) = f;
cout << g(a,b) << endl;

return 0;
}

#include <iostream>
using namespace std;

int f (int x, int y) { return y-x; }

int main()
{
int a = 5, b = 6, f(int, int), (*g)(int, int) = f; //此处 g 是所谓“函数指针”指向 f 函数
cout << g(a,b) << endl; //所以此地的 g(a,b) 等价于 f(a,b)
return 0;
}