Reading the C++ Standard, i see that there are "function" types and "pointer to function" types:

typedef int func(int);     // function
typedef int (*pfunc)(int); // pointer to function
typedef func* pfunc;       // same as above

I have never seen the function types used outside of examples (or maybe i didn't recognize their usage?). Some examples:

func increase, decrease;            // declares two functions
int increase(int), decrease(int);   // same as above

int increase(int x) {return x + 1;} // cannot use the typedef when defining functions
int decrease(int x) {return x - 1;} // cannot use the typedef when defining functions

struct mystruct
{
    func add, subtract, multiply;   // declares three member functions
    int member;
};

int mystruct::add(int x) {return x + member;} // cannot use the typedef
int mystruct::subtract(int x) {return x - member;}

int main()
{
    func k; // the syntax is correct but the variable k is useless!
    mystruct myobject;
    myobject.member = 4;

    cout << increase(5) << ' ' << decrease(5) << '\n'; // outputs 6 and 4
    cout << myobject.add(5) << ' ' << myobject.subtract(5) << '\n'; // 9 and 1
}

Seeing that the function types support syntax that doesn't appear in C (declaring member functions), i guess they are not just a part of C baggage that C++ has to support for backward compatibility.

So is there any use for function types, other than demonstrating some funky syntax?