std::function<R(Args...)>::target_type

From cppreference.com
< cpp‎ | utility‎ | functional‎ | function
C++
Utilities library
General utilities
Relational operators (deprecated in C++20)
Integer comparison functions
(C++20)(C++20)(C++20)
(C++20)
Swap and type operations
(C++20)
(C++14)
(C++11)
(C++23)
(C++11)
(C++23)
(C++11)
(C++11)
(C++17)
Common vocabulary types
(C++11)
(C++17)
(C++17)
(C++17)
(C++11)
(C++11)
(C++17)
(C++17)
(C++23)



Function objects
Function invocation
(C++17)(C++23)
Identity function object
(C++20)
Transparent operator wrappers
(C++14)
(C++14)
(C++14)
(C++14)  
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)
(C++14)

Old binders and adaptors
(until C++17*)
(until C++17*)
(until C++17*)
(until C++17*)
(until C++17*)  
(until C++17*)
(until C++17*) (until C++17*) (until C++17*) (until C++17*)
(until C++20*)
(until C++20*)
(until C++17*)(until C++17*)
(until C++17*)(until C++17*)

(until C++17*)
(until C++17*) (until C++17*) (until C++17*) (until C++17*)
(until C++20*)
(until C++20*)
std::function
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

 obtains a pointer to the stored target
(public member function)
contains some type’s information, the class returned by the typeid operator
(class)
typeid queries information of a type, returning a std::type_info object representing the type
(operator)
Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/utility/functional/function/target_type&oldid=176892