std::remove_cv, std::remove_const, std::remove_volatile – cppreference.com

Aus cppreference.com

definiert in Header `<type_traits>`

`template< class T > struct remove_cv;`	(1)	(seit C++11)

`template< class T > struct remove_const;`	(2)	(seit C++11)

`template< class T > struct remove_volatile;`	(3)	(seit C++11)

Provides the member typedef type which is the same as T, except that its topmost cv-qualifiers are removed.

1) removes the topmost const, the topmost volatile, or both, if present.

2) removes the topmost const

3) removes the topmost volatile

Mitglied Typen


Name Original: Name The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions.	Definition

`type`	the type `T` without cv-qualifier

Mögliche Implementierung

template< class T >
struct remove_cv {
    typedef typename std::remove_volatile<typename std::remove_const<T>::type>::type type;
};

template< class T > struct remove_const          { typedef T type; };
template< class T > struct remove_const<const T> { typedef T type; };

template< class T > struct remove_volatile             { typedef T type; };
template< class T > struct remove_volatile<volatile T> { typedef T type; };

Beispiel

Removing const/volatile from const volatile int * does not modify the type, because the pointer itself is neither const nor volatile.

#include <iostream>
#include <type_traits>
 
int main() {
    typedef std::remove_cv<const int>::type type1;
    typedef std::remove_cv<volatile int>::type type2;
    typedef std::remove_cv<const volatile int>::type type3;
    typedef std::remove_cv<const volatile int*>::type type4;
    typedef std::remove_cv<int * const volatile>::type type5;
 
    std::cout << "test1 " << (std::is_same<int, type1>::value
        ? "passed" : "failed") << '\n';
    std::cout << "test2 " << (std::is_same<int, type2>::value
        ? "passed" : "failed") << '\n';
    std::cout << "test3 " << (std::is_same<int, type3>::value
        ? "passed" : "failed") << '\n';
    std::cout << "test4 " << (std::is_same<const volatile int*, type4>::value
        ? "passed" : "failed") << '\n';
    std::cout << "test5 " << (std::is_same<int*, type5>::value
        ? "passed" : "failed") << '\n';
}

Output:

test1 passed
test2 passed
test3 passed
test4 passed
test5 passed

Siehe auch


	prüft, ob ein Typ const qualifizierten Original: checks if a type is const-qualified The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (Klassen-Template) [edit]

	prüft, ob ein Typ flüchtigen qualifiziert Original: checks if a type is volatile-qualified The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (Klassen-Template) [edit]