< cpp‎ | types
Metaprogramming library
Type traits
Type categories
Type properties
(C++11)(until C++20*)
(C++11)(deprecated in C++20)
Type trait constants
Supported operations
Relationships and property queries
Type modifications
Type transformations
(C++11)(deprecated in C++23)
(C++11)(deprecated in C++23)

(C++11)(until C++20*)(C++17)
Compile-time rational arithmetic
Compile-time integer sequences
Defined in header <type_traits>
template< class T >
struct add_pointer;
(since C++11)

If T is a referenceable type or (possibly cv-qualified) void, the member typedef type provided is typename std::remove_reference::type<T>*.

Otherwise, the member typedef type provided is T.

If the program adds specializations for std::add_pointer, the behavior is undefined.


[edit] Nested types

Name Definition
type determined as above

[edit] Helper types

template< class T >
using add_pointer_t = typename add_pointer<T>::type;
(since C++14)

[edit] Possible implementation

namespace detail
    template<class T>
    struct type_identity { using type = T; }; // or use std::type_identity (since C++20)
    template<class T>
    auto try_add_pointer(int)
      -> type_identity<typename std::remove_reference<T>::type*>; // usual case
    template<class T>
    auto try_add_pointer(...)
      -> type_identity<T>; // unusual case (cannot form std::remove_reference<T>::type*)
} // namespace detail
template<class T>
struct add_pointer : decltype(detail::try_add_pointer<T>(0)) {};

[edit] Example

#include <iostream>
#include <type_traits>
template<typename F, typename Class>
void ptr_to_member_func_cvref_test(F Class::*)
    // F is an “abominable function type”
    using FF = std::add_pointer_t<F>;
    static_assert(std::is_same_v<F, FF>, "FF should be precisely F");
struct S
    void f_ref() & {}
    void f_const() const {}
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_v<IntPtr>, "IntPtr should be a pointer");
    static_assert(std::is_same_v<IntPtr, int*>, "IntPtr should be a pointer to int");
    static_assert(std::is_same_v<IntPtr2, IntPtr>, "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_v<IntAgain>, "IntAgain should not be a pointer");
    static_assert(std::is_same_v<IntAgain, int>, "IntAgain should be equal to int");


i = 123
*pi = 123
j = 123

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 2101 C++11 the program was ill-formed if T is a function type with cv or ref the type produced is T in this case

[edit] See also

checks if a type is a pointer type
(class template) [edit]
removes a pointer from the given type
(class template) [edit]