std::is_pointer

 

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Type categories is_void (C++11) is_null_pointer (C++11)(DR*) 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_reference (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_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_constantbool_constanttrue_typefalse_type (C++11)(C++17)(C++11)(C++11) Metafunctions conjunction (C++17) disjunction (C++17) negation (C++17)	Supported operations is_constructibleis_trivially_constructibleis_nothrow_constructible (C++11)(C++11)(C++11) is_default_constructibleis_trivially_default_constructibleis_nothrow_default_constructible (C++11)(C++11)(C++11) is_copy_constructibleis_trivially_copy_constructibleis_nothrow_copy_constructible (C++11)(C++11)(C++11) is_move_constructibleis_trivially_move_constructibleis_nothrow_move_constructible (C++11)(C++11)(C++11) is_assignableis_trivially_assignableis_nothrow_assignable (C++11)(C++11)(C++11) is_copy_assignableis_trivially_copy_assignableis_nothrow_copy_assignable (C++11)(C++11)(C++11) is_move_assignableis_trivially_move_assignableis_nothrow_move_assignable (C++11)(C++11)(C++11) is_destructibleis_trivially_destructibleis_nothrow_destructible (C++11)(C++11)(C++11) has_virtual_destructor (C++11) is_swappable_withis_swappableis_nothrow_swappable_withis_nothrow_swappable (C++17)(C++17)(C++17)(C++17) Relationships and property queries is_same (C++11) is_convertibleis_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_invocableis_invocable_ris_nothrow_invocableis_nothrow_invocable_r (C++17)(C++17)(C++17)(C++17) Type modifications remove_cvremove_constremove_volatile (C++11)(C++11)(C++11) add_cvadd_constadd_volatile (C++11)(C++11)(C++11) make_signed (C++11) make_unsigned (C++11) remove_reference (C++11) add_lvalue_referenceadd_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) result_ofinvoke_result (C++11)(until C++20*)(C++17) conditional (C++11) common_type (C++11) common_reference (C++20) underlying_type (C++11) type_identity (C++20) enable_if (C++11) void_t (C++17)
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

T

-

a type to check

Helper variable template

template<class T > constexprbool is_pointer_v = is_pointer<T>::value;		(since C++17)

Inherited from std::integral_constant

Member constants

value [static]

true if T 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*constvolatile>: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 datavoid(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(*)()>);}

See also

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)