std::function::target_type(3)

NAME
std::function::target_type - std::function::target_type

Synopsis
   const std::type_info& target_type() const noexcept; (since C++11)
   Returns the type of the stored function.

Parameters
   (none)

Return value
   typeid(T) if the stored function has type T, otherwise typeid(void)

Example
// Run this code
 #include <functional>
 #include <iostream>
 int f(int a) { return -a; }
 void g(double) {}
 int main()
 {
     // fn1 and fn2 have the same type, but their targets do not
     std::function<int(int)> fn1(f),
                        fn2([](int a) {return -a;});
     std::cout << fn1.target_type().name() << '\n'
               << fn2.target_type().name() << '\n';
     // since C++17 deduction guides (CTAD) can avail
     std::cout << std::function{g}.target_type().name() << '\n';
 }

Possible output:
 PFiiE
 Z4mainEUliE_
 PFvdE

See also
   target obtains a pointer to the stored target
             (public member function)
   typeid Queries information of a type, returning a std::type_info object
             representing the type.
             contains some type's information, generated by the implementation.
   type_info This is the class returned by the typeid operator.
             (class)