std:: is_pointer

From cppreference.com

Type traits

Type categories

is_void (C++11)
is_null_pointer (C++14)
is_array (C++11)
is_pointer (C++11)
is_enum (C++11)
is_union (C++11)
is_class (C++11)
is_function (C++11)

is_object (C++11)
is_scalar (C++11)
is_compound (C++11)
is_integral (C++11)
is_floating_point (C++11)
is_fundamental (C++11)
is_arithmetic (C++11)

is_reference

(C++11)

is_lvalue_reference

(C++11)

is_rvalue_reference

(C++11)

is_member_pointer

(C++11)

is_member_object_pointer

(C++11)

is_member_function_pointer

(C++11)

Type properties

is_const

(C++11)

is_volatile

(C++11)

is_empty

(C++11)

is_polymorphic

(C++11)

is_final

(C++14)

is_abstract

(C++11)

is_aggregate

(C++17)

is_implicit_lifetime

(C++23)

is_trivial

(C++11) (deprecated in C++26)

is_trivially_copyable

(C++11)

is_standard_layout

(C++11)

is_literal_type

(C++11) ( until C++20* )

is_pod

(C++11) (deprecated in C++20)

is_signed

(C++11)

is_unsigned

(C++11)

is_bounded_array

(C++20)

is_unbounded_array

(C++20)

is_scoped_enum

(C++23)

has_unique_object_representations

(C++17)

Type trait constants

integral_constant bool_constant true_type false_type

(C++11) (C++17) (C++11) (C++11)

Metafunctions

conjunction

(C++17)

disjunction

(C++17)

negation

(C++17)

Supported operations

is_constructible is_trivially_constructible is_nothrow_constructible (C++11) (C++11) (C++11)
is_default_constructible is_trivially_default_constructible is_nothrow_default_constructible (C++11) (C++11) (C++11)
is_copy_constructible is_trivially_copy_constructible is_nothrow_copy_constructible (C++11) (C++11) (C++11)
is_move_constructible is_trivially_move_constructible is_nothrow_move_constructible (C++11) (C++11) (C++11)
is_assignable is_trivially_assignable is_nothrow_assignable (C++11) (C++11) (C++11)

is_copy_assignable is_trivially_copy_assignable is_nothrow_copy_assignable (C++11) (C++11) (C++11)
is_move_assignable is_trivially_move_assignable is_nothrow_move_assignable (C++11) (C++11) (C++11)
is_destructible is_trivially_destructible is_nothrow_destructible (C++11) (C++11) (C++11)
has_virtual_destructor (C++11)
is_swappable_with is_swappable is_nothrow_swappable_with is_nothrow_swappable (C++17) (C++17) (C++17) (C++17)

Relationships and property queries

is_same (C++11)
is_convertible is_nothrow_convertible (C++11) (C++20)
is_layout_compatible (C++20)
is_pointer_interconvertible_base_of (C++20)
is_pointer_interconvertible_with_class (C++20)
is_corresponding_member (C++20)
reference_constructs_from_temporary (C++23)
reference_converts_from_temporary (C++23)

is_base_of (C++11)
is_virtual_base_of (C++26)
alignment_of (C++11)
rank (C++11)
extent (C++11)
is_invocable is_invocable_r is_nothrow_invocable is_nothrow_invocable_r (C++17) (C++17) (C++17) (C++17)

Type modifications

remove_cv remove_const remove_volatile (C++11) (C++11) (C++11)
add_cv add_const add_volatile (C++11) (C++11) (C++11)
make_signed (C++11)
make_unsigned (C++11)

remove_reference (C++11)
add_lvalue_reference add_rvalue_reference (C++11) (C++11)
remove_pointer (C++11)
add_pointer (C++11)
remove_extent (C++11)
remove_all_extents (C++11)

Type transformations

aligned_storage (C++11) (deprecated in C++23)
aligned_union (C++11) (deprecated in C++23)
decay (C++11)
remove_cvref (C++20)
enable_if (C++11)
void_t (C++17)

conditional (C++11)
common_type (C++11)
common_reference (C++20)
underlying_type (C++11)
result_of invoke_result (C++11) ( until C++20* ) (C++17)
type_identity (C++20)

Compile-time rational arithmetic

Compile-time integer sequences

integer_sequence

(C++14)

Defined in header `<type_traits>`
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.

Template parameters

a type to check

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

value

[static]

true if

is a pointer type, false otherwise
(public static member constant)

Member functions

operator bool	converts the object to bool , returns value (public member function)
operator() (C++14)	returns value (public member function)

Member types

Type	Definition
`value_type`	bool
`type`	std:: integral_constant < bool , value >

Possible implementation

template<class T>
struct is_pointer : std::false_type {};
 
template<class T>
struct is_pointer<T*> : std::true_type {};
 
template<class T>
struct is_pointer<T* const> : std::true_type {};
 
template<class T>
struct is_pointer<T* volatile> : std::true_type {};
 
template<class T>
struct is_pointer<T* const volatile> : std::true_type {};

Example

Run this code

#include <type_traits>
 
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<A>::value
        && ! std::is_pointer_v<A>    // same thing as above, but in C++17!
        && ! std::is_pointer<A>()    // same as above, using inherited operator bool
        && ! std::is_pointer<A>{}    // ditto
        && ! std::is_pointer<A>()()  // same as above, using inherited operator()
        && ! std::is_pointer<A>{}()  // 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<int>
        &&   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 (*)()>
    );
}

Compiler support
Freestanding and hosted
Language
Standard library
Standard library headers
Named requirements
Feature test macros (C++20)
Language support library
Concepts library (C++20)
Metaprogramming library (C++11)
Diagnostics library
General utilities library
Strings library
Containers library
Iterators library
Ranges library (C++20)
Algorithms library
Numerics library
Localizations library
Input/output library
Filesystem library (C++17)
Regular expressions library (C++11)
Concurrency support library (C++11)
Execution support library (C++26)
Technical specifications
Symbols index
External libraries

std:: is_pointer

Template parameters

Helper variable template

Inherited from std:: integral_constant

Member constants

Member functions

Member types

Possible implementation

Example

See also

Navigation

is_member_pointer (C++11)	checks if a type is a pointer to a non-static member function or object (class template)
is_member_object_pointer (C++11)	checks if a type is a non-static member object pointer (class template)
is_member_function_pointer (C++11)	checks if a type is a non-static member function pointer (class template)
is_array (C++11)	checks if a type is an array type (class template)
is_scalar (C++11)	checks if a type is a scalar type (class template)