C syntax for functions returning function pointers

Question

Consider the following typedefs :

typedef int (*f1)(float);
typedef f1 (*f2)(double);
typedef f2 (*f3)(int);

f2 is a function

Answer 1

Use std::function:

typedef std::function f1;
typedef std::function f2;
typedef std::function    f3;

or

typedef std::function(double)>(int)> f3;