Type support (basic types, RTTI, type traits)
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< cpp
(See also type for type system overview)
Contents |
[edit] Basic types
[edit] Fundamental types defined by the language
[edit] Additional basic types and macros
Defined in header
<cstddef> |
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unsigned integer type returned by the sizeof operator (typedef) |
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signed integer type returned when subtracting two pointers (typedef) |
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(C++11)
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the type of the null pointer literal nullptr (typedef) |
implementation-defined null pointer constant (macro constant) |
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(C++11)
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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) |
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Defined in header
<cstdbool> |
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__bool_true_false_are_defined
(C++11)
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C compatibility macro constant, expands to integer constant 1 (macro constant) |
Defined in header
<cstdalign> |
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__alignas_is_defined
(C++11)
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C compatibility macro constant, expands to integer constant 1 (macro constant) |
[edit] Fixed width integer types (since C++11)
[edit] Numeric limits
Defined in header
<limits> |
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provides an interface to query properties of all fundamental numeric types. (class template) |
[edit] C numeric limits interface
[edit] Runtime type identification
contains some type's information, generated by the implementation. This is the class returned by the typeid operator. (class) |
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(C++11)
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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) |
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exception that is thrown by an invalid dynamic_cast expression, i.e. a cast of reference type fails (class) |
[edit] Type traits (since C++11)
Type traits defines an 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.
[edit] Type properties
Defined in header
<type_traits> |
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Primary type categories |
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(C++11)
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checks if a type is void (class template) |
(C++14)
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checks if a type is std::nullptr_t (class template) |
(C++11)
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checks if a type is integral type (class template) |
(C++11)
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checks if a type is floating-point type (class template) |
(C++11)
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checks if a type is an array type (class template) |
(C++11)
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checks if a type is an enumeration type (class template) |
(C++11)
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checks if a type is an union type (class template) |
(C++11)
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checks if a type is a class type (but not union type) (class template) |
(C++11)
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checks if a type is a function type (class template) |
(C++11)
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checks if a type is a pointer type (class template) |
(C++11)
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checks if a type is lvalue reference (class template) |
(C++11)
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checks if a type is rvalue reference (class template) |
(C++11)
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checks if a type is a pointer to a non-static member object (class template) |
(C++11)
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checks if a type is a pointer to a non-static member function (class template) |
Composite type categories |
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(C++11)
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checks if a type is fundamental type (class template) |
(C++11)
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checks if a type is arithmetic type (class template) |
(C++11)
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checks if a type is scalar type (class template) |
(C++11)
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checks if a type is object type (class template) |
(C++11)
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checks if a type is compound type (class template) |
(C++11)
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checks if a type is either lvalue reference or rvalue reference (class template) |
(C++11)
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checks if a type is a pointer to a non-static member function or object (class template) |
Type properties |
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(C++11)
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checks if a type is const-qualified (class template) |
(C++11)
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checks if a type is volatile-qualified (class template) |
(C++11)
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checks if a type is trivial (class template) |
(C++11)
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checks if a type is trivially copyable (class template) |
(C++11)
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checks if a type is standard-layout type (class template) |
(C++11)
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checks if a type is plain-old data (POD) type (class template) |
(C++11)
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checks if a type is literal type (class template) |
(C++11)
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checks if a type is class (but not union) type and has no data (class template) |
(C++11)
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checks if a type is polymorphic class type (class template) |
(C++14)
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checks if a type is a final class type (class template) |
(C++11)
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checks if a type is abstract class type (class template) |
(C++11)
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checks if a type is signed arithmetic type (class template) |
(C++11)
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checks if a type is unsigned arithmetic type (class template) |
Supported operations |
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(C++11)(C++11)(C++11)
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checks if a type has a constructor for specific arguments (class template) |
checks if a type has a default constructor (class template) |
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(C++11)(C++11)(C++11)
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checks if a type has a copy constructor (class template) |
(C++11)(C++11)(C++11)
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checks if a type has a move constructor (class template) |
(C++11)(C++11)(C++11)
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checks if a type has a assignment operator for a specific argument (class template) |
(C++11)(C++11)(C++11)
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checks if a type has a copy assignment operator (class template) |
(C++11)(C++11)(C++11)
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checks if a type has a move assignment operator (class template) |
(C++11)(C++11)(C++11)
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checks if a type has a non-deleted destructor (class template) |
(C++11)
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checks if a type has a virtual destructor (class template) |
Property queries |
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(C++11)
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obtains the type's alignment requirements (class template) |
(C++11)
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obtains the number of dimensions of an array type (class template) |
(C++11)
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obtains the size of an array type along a specified dimension (class template) |
Type relationships |
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(C++11)
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checks if two types are the same (class template) |
(C++11)
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checks if a type is derived from the other type (class template) |
(C++11)
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checks if a type can be converted to the other type (class template) |
[edit] 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> |
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Const-volatility specifiers |
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(C++11)(C++11)(C++11)
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removes const or/and volatile specifiers from the given type (class template) |
(C++11)(C++11)(C++11)
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adds const or/and volatile specifiers to the given type (class template) |
References |
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(C++11)
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removes reference from the given type (class template) |
(C++11)(C++11)
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adds lvalue or rvalue reference to the given type (class template) |
Pointers |
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(C++11)
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removes pointer from the given type (class template) |
(C++11)
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adds pointer to the given type (class template) |
Sign modifiers |
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(C++11)
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makes the given integral type signed (class template) |
(C++11)
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makes the given integral type unsigned (class template) |
Arrays |
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(C++11)
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removes one extent from the given array type (class template) |
(C++11)
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removes all extents from the given array type (class template) |
[edit] Miscellaneous transformations
Defined in header
<type_traits> |
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(C++11)
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defines the type suitable for use as uninitialized storage for types of given size (class template) |
(C++11)
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defines the type suitable for use as uninitialized storage for all given types (class template) |
(C++11)
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applies type transformations as when passing a function argument by value (class template) |
(C++11)
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hides a function overload or template specialization based on compile-time boolean (class template) |
(C++11)
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chooses one type or another based on compile-type boolean (class template) |
(C++11)
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deduces the result type of a mixed-mode arithmetic expression (class template) |
(C++11)
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obtains the underlying integer type for a given enumeration type (class template) |
(C++11)
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deduces the return type of a function call expression (class template) |
(C++17)
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void variadic alias template (alias template) |
[edit] Helper classes
Defined in header
<type_traits> |
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(C++11)(C++17)
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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> |
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Type | Definition |
true_type
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std::integral_constant<bool, true> |
false_type
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std::integral_constant<bool, false> |
[edit] See also
C documentation for Type support library
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