(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) | POD 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) | |
| Defined in header <cstdbool> | |
| __bool_true_false_are_defined (C++11) | C compatibility macro constant, expands to integer constant 1 (macro constant) |
| Defined in header <cstdalign> | |
| __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
| contains some type's information, generated by the implementation. This is the class returned by the typeid operator. (class) | |
| (C++11) | wrapper around a type_info object, that can be used as index in associative and unordered associative containers (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) |
Type traits (since C++11)
Type traits defines a compile-time template-based interface to query or modify the properties of types.
Any attempt to specialize any of the class templates listed in this section results in undefined behavior, except that std::common_type may be specialized if the specialization depends on a user-defined type.
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) | checks if a type is plain-old data (POD) type (class template) |
| (C++11) | checks if a type is literal type (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++14) | checks if a type is a final class type (class template) |
| (C++11) | checks if a type is abstract class 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) |
| 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 has a move constructor (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) |
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) | checks if a type can be converted to the other type (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++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-type boolean (class template) |
| (C++11) | deduces the result type of a mixed-mode arithmetic expression (class template) |
| (C++11) | obtains the underlying integer type for a given enumeration type (class template) |
| (C++11) | deduces the return type of a function call expression (class template) |
| (C++17) | void variadic alias template (alias 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> |
See also
C documentation for Type support library |
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