#Assigning a std::function from the functional library to the identity

19 messages · Page 1 of 1 (latest)

leaden bramble
#

so there's supposed to be a std::identity in functional, but I can't figure out how to assign it to a std::function

#include <functional>
#include <iostream>

int main()
{
    long double val = 20;
    std::function<long double(long double)> f;

    f = std::identity;

    std::cout << f(val);
    
    return 0;
}```
This is the error I get `namespace "std" has no member "identity"`
But the console should output `20`, of course
crystal karmaBOT
#

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lone quest
#

!cppref identity

crystal karmaBOT
lone quest
#

identity is a type, not an object

leaden bramble
#

would the best solution just be to write my own identity function, or is there a std object that does that

#

ofc it'd be very easy, but std is standard yk

lone quest
#

Try
std::identity{}

#

Like create an identity object

leaden bramble
#

Like this?

int main()
{
    long double val = 20;
    std::function<long double(long double)> f;

    f = std::identity{};

    cout << f(val);
    
    return 0;
}

I get these errors
'identity': is not a member of 'std'
'identity': undeclared identifier
expected a ';'
namespace "std" has no member "identity"

torpid panther
#

;compile -includeiostream -includefunctional -std=c++20

int main()
{
    long double val = 20;
    std::function<long double(long double)> f;

    f = std::identity{};

    std::cout << f(val);
    
    return 0;
}
tender stagBOT
#
Program Output
20
charaverk | 31ms | c++ | x86-64 gcc 15.1 | godbolt.org
leaden bramble
#

oh thats cool, didn't know we could do that

torpid panther
#

do you got it?

leaden bramble
#

yesss

#

thank yall

#

!solved