std::is_pointer - cppreference.com (original) (raw)
| | | | | ---------------------------------------- | | ------------- | | template< class T > struct is_pointer; | | (since C++11) |
std::is_pointer is a UnaryTypeTrait.
Checks whether T is a pointer to object or function (including pointer to void, but excluding pointer to member) or a cv-qualified version thereof. Provides the member constant value which is equal to true, if T is an object/function pointer type. Otherwise, value is equal to false.
If the program adds specializations for std::is_pointer or std::is_pointer_v, the behavior is undefined.
Contents
[edit] Template parameters
[edit] Helper variable template
| template< class T > constexpr bool is_pointer_v = is_pointer<T>::value; | | (since C++17) | | ----------------------------------------------------------------------------- | | ------------- |
Inherited from std::integral_constant
Member constants
| | true if T is a pointer type, false otherwise (public static member constant) | | ------------------------------------------------------------------------------- |
Member functions
| | converts the object to bool, returns value (public member function) | | ---------------------------------------------------------------------- | | | returns value (public member function) |
Member types
[edit] Possible implementation
[edit] Example
#include int main() { struct A { int m; void f() {} }; int A::*mem_data_ptr = &A::m; // a pointer to member data void (A::*mem_fun_ptr)() = &A::f; // a pointer to member function static_assert( ! std::is_pointer::value && ! std::is_pointer_v // same thing as above, but in C++17! && ! std::is_pointer() // same as above, using inherited operator bool && ! std::is_pointer{} // ditto && ! std::is_pointer()() // same as above, using inherited operator() && ! std::is_pointer{}() // ditto && std::is_pointer_v<A*> && std::is_pointer_v<A const* volatile> && ! std::is_pointer_v<A&> && ! std::is_pointer_v<decltype(mem_data_ptr)> && ! std::is_pointer_v<decltype(mem_fun_ptr)> && std::is_pointer_v<void*> && ! std::is_pointer_v && std::is_pointer_v<int*> && std::is_pointer_v<int**> && ! std::is_pointer_v<int[10]> && ! std::is_pointer_v<std::nullptr_t> && std::is_pointer_v<void (*)()> ); }