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Type support (basic types, RTTI, type traits)

(See also type for type system overview).

Basic types

Fundamental types defined by the language

Additional basic types and macros

Defined in header <cstddef>
unsigned integer type returned by the sizeof operator
(typedef)
signed integer type returned when subtracting two pointers
(typedef)
(C++11)
 the type of the null pointer literal nullptr
(typedef)
implementation-defined null pointer constant
(macro constant)
(C++11)
 trivial type with alignment requirement as great as any other scalar type
(typedef)
byte offset from the beginning of a standard-layout type to specified member
(function macro)
(C++17)
 the byte type
(enum)
Defined in header <cstdbool> (until C++20)
Defined in header <stdbool.h>
__bool_true_false_are_defined
(C++11)
 C compatibility macro constant, expands to integer constant 1
(macro constant)
Defined in header <cstdalign> (until C++20)
Defined in header <stdalign.h>
__alignas_is_defined
(C++11)
 C compatibility macro constant, expands to integer constant 1
(macro constant)

Fixed width integer types (since C++11)

Numeric limits

Defined in header <limits>
provides an interface to query properties of all fundamental numeric types.
(class template)

C numeric limits interface

Runtime type identification

Defined in header <typeinfo>
contains some type's information, generated by the implementation.
This is the class returned by the typeid operator.
(class)
exception that is thrown if an argument in a typeid expression is null
(class)
exception that is thrown by an invalid dynamic_cast expression, i.e. a cast of reference type fails
(class)
Defined in header <typeindex>
(C++11)
 wrapper around a type_info object, that can be used as index in associative and unordered associative containers
(class)

Type traits (since C++11)

Type traits defines a compile-time template-based interface to query or modify the properties of types.

Attempting to specialize a template defined in the <type_traits> header results in undefined behavior, except that std::common_type may be specialized as described in its description.

A template defined in the <type_traits> header may be instantiated with an incomplete type unless otherwise specified, notwithstanding the general prohibition against instantiating standard library templates with incomplete types.

Type properties

Defined in header <type_traits>
Primary type categories
(C++11)
 checks if a type is void
(class template)
(C++14)
 checks if a type is std::nullptr_t
(class template)
(C++11)
 checks if a type is integral type
(class template)
(C++11)
 checks if a type is floating-point type
(class template)
(C++11)
 checks if a type is an array type
(class template)
(C++11)
 checks if a type is an enumeration type
(class template)
(C++11)
 checks if a type is an union type
(class template)
(C++11)
 checks if a type is a non-union class type
(class template)
(C++11)
 checks if a type is a function type
(class template)
(C++11)
 checks if a type is a pointer type
(class template)
(C++11)
 checks if a type is lvalue reference
(class template)
(C++11)
 checks if a type is rvalue reference
(class template)
(C++11)
 checks if a type is a pointer to a non-static member object
(class template)
(C++11)
 checks if a type is a pointer to a non-static member function
(class template)
Composite type categories
(C++11)
 checks if a type is fundamental type
(class template)
(C++11)
 checks if a type is arithmetic type
(class template)
(C++11)
 checks if a type is scalar type
(class template)
(C++11)
 checks if a type is object type
(class template)
(C++11)
 checks if a type is compound type
(class template)
(C++11)
 checks if a type is either lvalue reference or rvalue reference
(class template)
(C++11)
 checks if a type is a pointer to a non-static member function or object
(class template)
Type properties
(C++11)
 checks if a type is const-qualified
(class template)
(C++11)
 checks if a type is volatile-qualified
(class template)
(C++11)
 checks if a type is trivial
(class template)
(C++11)
 checks if a type is trivially copyable
(class template)
(C++11)
 checks if a type is standard-layout type
(class template)
(C++11)(deprecated in C++20)
 checks if a type is plain-old data (POD) type
(class template)
(C++11)(deprecated in C++17)
 checks if a type is literal type
(class template)
(C++17)
 checks if every bit in the type's object representation contributes to its value
(class template)
(C++11)
 checks if a type is class (but not union) type and has no data
(class template)
(C++11)
 checks if a type is polymorphic class type
(class template)
(C++11)
 checks if a type is abstract class type
(class template)
(C++14)
 checks if a type is a final class type
(class template)
(C++17)
 checks if a type is an aggregate type
(class template)
(C++11)
 checks if a type is signed arithmetic type
(class template)
(C++11)
 checks if a type is unsigned arithmetic type
(class template)
Supported operations
(C++11)(C++11)(C++11)
 checks if a type has a constructor for specific arguments
(class template)
(C++11)(C++11)(C++11)
 checks if a type has a default constructor
(class template)
(C++11)(C++11)(C++11)
 checks if a type has a copy constructor
(class template)
(C++11)(C++11)(C++11)
 checks if a type can be constructed from an rvalue reference
(class template)
(C++11)(C++11)(C++11)
 checks if a type has a assignment operator for a specific argument
(class template)
(C++11)(C++11)(C++11)
 checks if a type has a copy assignment operator
(class template)
(C++11)(C++11)(C++11)
 checks if a type has a move assignment operator
(class template)
(C++11)(C++11)(C++11)
 checks if a type has a non-deleted destructor
(class template)
(C++11)
 checks if a type has a virtual destructor
(class template)
(C++17)(C++17)(C++17)(C++17)
 checks if objects of a type can be swapped with objects of same or different type
(class template)
Property queries
(C++11)
 obtains the type's alignment requirements
(class template)
(C++11)
 obtains the number of dimensions of an array type
(class template)
(C++11)
 obtains the size of an array type along a specified dimension
(class template)
Type relationships
(C++11)
 checks if two types are the same
(class template)
(C++11)
 checks if a type is derived from the other type
(class template)
(C++11)(C++20)
 checks if a type can be converted to the other type
(class template)
(C++17)
 checks if a type can be invoked (as if by std::invoke) with the given argument types
(class template)

Type modifications

Type modification templates create new type definitions by applying modifications on a template parameter. The resulting type can then be accessed through type member typedef.

Defined in header <type_traits>
Const-volatility specifiers
(C++11)(C++11)(C++11)
 removes const or/and volatile specifiers from the given type
(class template)
(C++11)(C++11)(C++11)
 adds const or/and volatile specifiers to the given type
(class template)
References
(C++11)
 removes reference from the given type
(class template)
(C++11)(C++11)
 adds lvalue or rvalue reference to the given type
(class template)
Pointers
(C++11)
 removes pointer from the given type
(class template)
(C++11)
 adds pointer to the given type
(class template)
Sign modifiers
(C++11)
 makes the given integral type signed
(class template)
(C++11)
 makes the given integral type unsigned
(class template)
Arrays
(C++11)
 removes one extent from the given array type
(class template)
(C++11)
 removes all extents from the given array type
(class template)

Miscellaneous transformations

Defined in header <type_traits>
(C++11)
 defines the type suitable for use as uninitialized storage for types of given size
(class template)
(C++11)
 defines the type suitable for use as uninitialized storage for all given types
(class template)
(C++11)
 applies type transformations as when passing a function argument by value
(class template)
(C++20)
 combines std::remove_cv and std::remove_reference
(class template)
(C++11)
 hides a function overload or template specialization based on compile-time boolean
(class template)
(C++11)
 chooses one type or another based on compile-time boolean
(class template)
(C++11)
 determines the common type of a group of types
(class template)
(C++20)
 determines the common reference type of a group of types
(class template)
(C++11)
 obtains the underlying integer type for a given enumeration type
(class template)
(C++11)(deprecated in C++17)(C++17)
 deduces the result type of invoking a callable object with a set of arguments
(class template)
(C++17)
 void variadic alias template
(alias template)
(C++20)
 returns the type argument unchanged
(class template)

Operations on traits

Defined in header <type_traits>
(C++17)
 variadic logical AND metafunction
(class template)
(C++17)
 variadic logical OR metafunction
(class template)
(C++17)
 logical NOT metafunction
(class template)

Helper classes

Defined in header <type_traits>
(C++11)(C++17)
 compile-time constant of specified type with specified value
(class template)

Two specializations of std::integral_constant for the type bool are provided:

Defined in header <type_traits>
Type Definition
true_type std::integral_constant<bool, true>
false_type std::integral_constant<bool, false>

Endian (since C++20)

Defined in header <type_traits>
Type Definition
(C++20)
 indicates the endianness of scalar types
(enum)

See also

C documentation for Type support library

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