std::remove_cv, std::remove_const, std::remove_volatile
From Cppreference
Defined in header <type_traits>
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template< class T >
struct remove_cv; |
(1) | (C++11 feature) |
template< class T >
struct remove_const; |
(2) | (C++11 feature) |
template< class T >
struct remove_volatile; |
(3) | (C++11 feature) |
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
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[edit] Member types
Name | Definition |
type | the type T without cv-qualifier |
[edit] Equivalent definition
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; }; |
[edit] Example
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> #include <typeinfo> 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 << (std::is_same<int, type1>::value ? "test1 passed" : "test1 failed") << '\n'; std::cout << (std::is_same<int, type2>::value ? "test2 passed" : "test2 failed") << '\n'; std::cout << (std::is_same<int, type3>::value ? "test3 passed" : "test3 failed") << '\n'; std::cout << (std::is_same<const volatile int*, type4>::value ? "test4 passed" : "test4 failed") << '\n'; std::cout << (std::is_same<int*, type5>::value ? "test5 passed" : "test5 failed") << '\n'; }
Output:
test1 passed test2 passed test3 passed test4 passed test5 passed
[edit] See also
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checks if a type is const-qualified (class template) |
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checks if a type is volatile-qualified (class template) |