The header <typeinfo> defines a type associated with type information generated by the implementation. It also defines two types for reporting dynamic type identification errors.
namespace std {
class type_info;
class bad_cast;
class bad_typeid;
}
See also: [expr.dynamic.cast], [expr.typeid].
namespace std {
class type_info {
public:
virtual ~type_info();
bool operator==(const type_info& rhs) const noexcept;
bool operator!=(const type_info& rhs) const noexcept;
bool before(const type_info& rhs) const noexcept;
size_t hash_code() const noexcept;
const char* name() const noexcept;
type_info(const type_info& rhs) = delete; // cannot be copied
type_info& operator=(const type_info& rhs) = delete; // cannot be copied
};
}
The class type_info describes type information generated by the implementation. Objects of this class effectively store a pointer to a name for the type, and an encoded value suitable for comparing two types for equality or collating order. The names, encoding rule, and collating sequence for types are all unspecified and may differ between programs.
Effects: Compares the current object with rhs.
Returns: true if the two values describe the same type.
bool operator!=(const type_info& rhs) const noexcept;
Returns: !(*this == rhs).
bool before(const type_info& rhs) const noexcept;
Effects: Compares the current object with rhs.
Returns: true if *this precedes rhs in the implementation's collation order.
size_t hash_code() const noexcept;
Returns: An unspecified value, except that within a single execution of the program, it shall return the same value for any two type_info objects which compare equal.
Remark: an implementation should return different values for two type_info objects which do not compare equal.
const char* name() const noexcept;
Remarks: The message may be a null-terminated multibyte string ([multibyte.strings]), suitable for conversion and display as a wstring ([string.classes], [locale.codecvt])
namespace std {
class bad_cast : public exception {
public:
bad_cast() noexcept;
bad_cast(const bad_cast&) noexcept;
bad_cast& operator=(const bad_cast&) noexcept;
virtual const char* what() const noexcept;
};
}
The class bad_cast defines the type of objects thrown as exceptions by the implementation to report the execution of an invalid dynamic-cast expression ([expr.dynamic.cast]).
Effects: Constructs an object of class bad_cast.
bad_cast(const bad_cast&) noexcept;
bad_cast& operator=(const bad_cast&) noexcept;
Effects: Copies an object of class bad_cast.
virtual const char* what() const noexcept;
Remarks: The message may be a null-terminated multibyte string ([multibyte.strings]), suitable for conversion and display as a wstring ([string.classes], [locale.codecvt])
namespace std {
class bad_typeid : public exception {
public:
bad_typeid() noexcept;
bad_typeid(const bad_typeid&) noexcept;
bad_typeid& operator=(const bad_typeid&) noexcept;
virtual const char* what() const noexcept;
};
}
The class bad_typeid defines the type of objects thrown as exceptions by the implementation to report a null pointer in a typeid expression ([expr.typeid]).
Effects: Constructs an object of class bad_typeid.
bad_typeid(const bad_typeid&) noexcept;
bad_typeid& operator=(const bad_typeid&) noexcept;
Effects: Copies an object of class bad_typeid.
virtual const char* what() const noexcept;
Remarks: The message may be a null-terminated multibyte string ([multibyte.strings]), suitable for conversion and display as a wstring ([string.classes], [locale.codecvt])