add_cv Class
Makes const volatile type from type.
Syntax
template <class T>
struct add_cv;
template <class T>
using add_cv_t = typename add_cv<T>::type;
Parameters
T
The type to modify.
Remarks
An instance of the modified type add_cv<T> has a type member typedef equivalent to T modified by both add_volatile and add_const, unless T already has the cv-qualifiers, is a reference, or is a function.
The add_cv_t<T> helper type is a shortcut to access the add_cv<T> member typedef type.
Example
// add_cv.cpp
// compile by using: cl /EHsc /W4 add_cv.cpp
#include <type_traits>
#include <iostream>
struct S {
void f() {
std::cout << "invoked non-cv-qualified S.f()" << std::endl;
}
void f() const {
std::cout << "invoked const S.f()" << std::endl;
}
void f() volatile {
std::cout << "invoked volatile S.f()" << std::endl;
}
void f() const volatile {
std::cout << "invoked const volatile S.f()" << std::endl;
}
};
template <class T>
void invoke() {
T t;
((T *)&t)->f();
}
int main()
{
invoke<S>();
invoke<std::add_const<S>::type>();
invoke<std::add_volatile<S>::type>();
invoke<std::add_cv<S>::type>();
}
invoked non-cv-qualified S.f()
invoked const S.f()
invoked volatile S.f()
invoked const volatile S.f()
Requirements
Header: <type_traits>
Namespace: std