std::add_const
Defined in header <type_traits> | | |
|---|---|---|
template< class T > struct add_cv; | (1) | (since C++11) |
template< class T > struct add_const; | (2) | (since C++11) |
template< class T > struct add_volatile; | (3) | (since C++11) |
提供成员类型胡枝子f。type这和T，但它的cv-限定符添加%28，除非T是一个函数，一个引用，或者已经有这个cv-限定符%29.
1%29加两者const和volatile...
2%29加const...
3%29加volatile...
成员类型
Name | Definition |
|---|---|
type | the type T with the cv-qualifier |
帮助者类型
template< class T > using add_cv_t = typename add_cv<T>::type; | | (since C++14) |
|---|---|---|
template< class T > using add_const_t = typename add_const<T>::type; | | (since C++14) |
template< class T > using add_volatile_t = typename add_volatile<T>::type; | | (since C++14) |
可能的实施
模板<class T>结构添加[医]CV<class T>结构添加[医]模板<class T>结构添加[医]易挥发的{tyduf挥发性T型；}；
*。
例
二次
#include <iostream>
#include <type_traits>
struct foo
{
void m() { std::cout << "Non-cv\n"; }
void m() const { std::cout << "Const\n"; }
};
template <class T>
void call_m()
{
T().m();
}
int main()
{
call_m<foo>();
call_m<std::add_const<foo>::type>();
}二次
产出：
二次
Non-cv
Const二次
另见
is_const (C++11) | checks if a type is const-qualified (class template) |
|---|---|
is_volatile (C++11) | checks if a type is volatile-qualified (class template) |
remove_cvremove_constremove_volatile (C++11)(C++11)(C++11) | removes const or/and volatile specifiers from the given type (class template) |
as_const (C++17) | obtains a reference to const to its argument (function template) |
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