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

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C++
Utilities library
General utilities
Relational operators (deprecated in C++20)
Function objects
Function invocation
(C++17) (C++23)
Identity function object
(C++20)
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* )
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( 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)
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