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<typeinfo>

Include the standard header <typeinfo> to define several types associated with the type-identification operator typeid, which yields information about both static and dynamic types.

namespace std {
class type_info;
class bad_cast;
class bad_typeid;
    };

bad_cast

class bad_cast : public exception {
    };

The class describes an exception thrown to indicate that a dynamic cast expression, of the form:

dynamic_cast<type>(expression)

generated a null pointer to initialize a reference. The value returned by what() is an implementation-defined C string. None of the member functions throw any exceptions.

bad_typeid

class bad_typeid : public exception {
    };

The class describes an exception thrown to indicate that a typeid operator encountered a null pointer. The value returned by what() is an implementation-defined C string. None of the member functions throw any exceptions.

type_info

class type_info {
public:
    virtual ~type_info();
    bool operator==(const type_info& right) const;
    bool operator!=(const type_info& right) const;
    bool before(const type_info& right) const;
    const char *name() const;
private:
    type_info(const type_info& right);
    type_info& operator=(const type_info& right);
    };

The class describes type information generated within the program 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, encoded values, and collating order for types are all unspecified and may differ between program executions.

An expression of the form typeid Ty is the only way to construct a (temporary) typeinfo object. The class has only a private copy constructor. Since the assignment operator is also private, you cannot copy or assign objects of class typeinfo either.

type_info::operator!=

bool operator!=(const type_info& right) const;

The function returns !(*this == right).

type_info::operator==

bool operator==(const type_info& right) const;

The function returns a nonzero value if *this and right represent the same type.

type_info::before

bool before(const type_info& right) const;

The function returns a nonzero value if *this precedes right in the collating order for types.

type_info::name

const char *name() const;

The function returns a C string which specifies the name of the type.

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Copyright © 1992-2002 by P.J. Plauger. All rights reserved.