Defined in header <type_traits> | ||
---|---|---|
template< class T > struct add_pointer; | (since C++11) |
If T
is a reference type, then provides the member typedef type
which is a pointer to the referred type.
Otherwise, if T names an object type, a function type that is not cv- or ref-qualified (since C++17), or a (possibly cv-qualified) void type, provides the member typedef type
which is the type T*
.
Otherwise (if T is a cv- or ref-qualified function type), provides the member typedef | (since C++17) |
Name | Definition |
---|---|
type | pointer to T or to the type referenced by T |
template< class T > using add_pointer_t = typename add_pointer<T>::type; | (since C++14) |
#include <iostream> #include <type_traits> int main() { int i = 123; int& ri = i; typedef std::add_pointer<decltype(i)>::type IntPtr; typedef std::add_pointer<decltype(ri)>::type IntPtr2; IntPtr pi = &i; std::cout << "i = " << i << "\n"; std::cout << "*pi = " << *pi << "\n"; static_assert(std::is_pointer<IntPtr>::value, "IntPtr should be a pointer"); static_assert(std::is_same<IntPtr, int*>::value, "IntPtr should be a pointer to int"); static_assert(std::is_same<IntPtr2, IntPtr>::value, "IntPtr2 should be equal to IntPtr"); typedef std::remove_pointer<IntPtr>::type IntAgain; IntAgain j = i; std::cout << "j = " << j << "\n"; static_assert(!std::is_pointer<IntAgain>::value, "IntAgain should not be a pointer"); static_assert(std::is_same<IntAgain, int>::value, "IntAgain should be equal to int"); }
Output:
(C++11) | checks if a type is a pointer type (class template) |
(C++11) | removes pointer from the given type (class template) |
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