C++ function pointer (class member) to non-static member function

Question

class Foo { public:     Foo() { do_something = &Foo::func_x; }      int (Foo::*do_something)(int);   // function pointer to class member function      void setFunc(bool e) { do_something = e ? &Foo::func_x : &Foo::func_y; }  private:     int func_x(int m) { return m *= 5; }     int func_y(int n) { return n *= 6; } };  int main() {     Foo f;     f.setFunc(false);     return (f.*do_something)(5);  // <- Not ok. Compile error. } 

How can I get this to work?

Answer 1

 class A{     public:         typedef int (A::*method)();          method p;         A(){             p = &A::foo;             (this->*p)(); // <- trick 1, inner call         }          int foo(){             printf("foo\n");             return 0;         }     };      void main()     {         A a;         (a.*a.p)(); // <- trick 2, outer call     } 

Answer 2

The line you want is

   return (f.*f.do_something)(5); 

(That compiles -- I've tried it)

"*f.do_something" refers to the pointer itself --- "f" tells us where to get the do_something value from. But we still need to give an object that will be the this pointer when we call the function. That's why we need the "f." prefix.