std::is_compound

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Metaprogramming library

Type traits

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

(C++11)

(C++11)

(C++11)

(C++11)

(C++14)

(C++11)

(C++17)

(C++23)

(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)

(C++11)

(C++11)

(C++20)

(C++20)

(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)

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Defined in header`<type_traits>`
template<class T> struct is_compound;		(since C++11)

std::is_compound is aUnaryTypeTrait.

IfT is a compound type (that is, array, function, object pointer, function pointer, member object pointer, member function pointer, reference, class, union, or enumeration, including any cv-qualified variants), provides the member constantvalue equaltrue. For any other type,value isfalse.

If the program adds specializations forstd::is_compound orstd::is_compound_v, the behavior is undefined.

[edit]Template parameters

a type to check

[edit]Helper variable template

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

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Inherited fromstd::integral_constant

Member constants

value

[static]

true ifT is a compound type,false otherwise
(public static member constant)

Member functions

operator bool	converts the object tobool, returnsvalue (public member function)
operator() (C++14)	returnsvalue (public member function)

Member types

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

[edit]Notes

Compound types are the types that are constructed from fundamental types. Any C++ type is either fundamental or compound.

[edit]Possible implementation

template<class T>struct is_compound:std::integral_constant<bool,!std::is_fundamental<T>::value>{};

[edit]Example

Run this code

#include <type_traits>#include <iostream> static_assert(not std::is_compound_v<int>);static_assert(std::is_compound_v<int*>);static_assert(std::is_compound_v<int&>); void f();static_assert(std::is_compound_v<decltype(f)>);static_assert(std::is_compound_v<decltype(&f)>); static_assert(std::is_compound_v<char[100]>); class C{};static_assert(std::is_compound_v<C>); union U{};static_assert(std::is_compound_v<U>); enumstruct E{ e};static_assert(std::is_compound_v<E>);static_assert(std::is_compound_v<decltype(E::e)>); struct S{int i:8;int j;void foo();};static_assert(not std::is_compound_v<decltype(S::i)>);static_assert(not std::is_compound_v<decltype(S::j)>);static_assert(std::is_compound_v<decltype(&S::j)>);static_assert(std::is_compound_v<decltype(&S::foo)>); int main(){std::cout<<"All checks have passed\n";}

[edit]See also

is_fundamental (C++11)	checks if a type is a fundamental type (class template)[edit]
is_scalar (C++11)	checks if a type is a scalar type (class template)[edit]
is_object (C++11)	checks if a type is an object type (class template)[edit]
is_array (C++11)	checks if a type is an array type (class template)[edit]