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<HTML><HEAD><TITLE><typeinfo></TITLE></HEAD><BODY><H1><A NAME="<typeinfo>"><CODE><typeinfo></CODE></A></H1><HR><P>Include the standard header <B><CODE><typeinfo></CODE></B>to define several types associated with the type-identification operator<B><A NAME="typeid"><CODE>typeid</CODE></A></B>,which yields information about both static and dynamic types.</P><PRE>namespace std {class <B><A HREF="#type_info">type_info</A></B>;class <B><A HREF="#bad_cast">bad_cast</A></B>;class <B><A HREF="#bad_typeid">bad_typeid</A></B>; };</PRE><H2><A NAME="bad_cast"><CODE>bad_cast</CODE></A></H2><PRE>class <B>bad_cast</B> : public <A HREF="exceptio.html#exception">exception</A> { };</PRE><P>The class describes an exception thrown to indicate that a<B><A NAME="dynamic cast">dynamic cast</A></B> expression,of the form:</P><PRE>dynamic_cast<type>(expression)</PRE><P>generated a null pointer to initialize a reference.The value returned by<CODE><A HREF="exceptio.html#exception::what">what</A>()</CODE>is an implementation-defined<A HREF="lib_over.html#C string">C string</A>.None of the member functions throw any exceptions.</P><H2><A NAME="bad_typeid"><CODE>bad_typeid</CODE></A></H2><PRE>class <B>bad_typeid</B> : public <A HREF="exceptio.html#exception">exception</A> { };</PRE><P>The class describes an exception thrown to indicate that a<A HREF="#typeid"><CODE>typeid</CODE></A> operator encountered anull pointer. The value returned by<CODE><A HREF="exceptio.html#exception::what">what</A>()</CODE>is an implementation-defined<A HREF="lib_over.html#C string">C string</A>.None of the member functions throw any exceptions.</P><H2><A NAME="type_info"><CODE>type_info</CODE></A></H2><PRE>class <B>type_info</B> {public: virtual <B>~type_info</B>(); bool <B><A HREF="#type_info::operator==">operator==</A></B>(const type_info& right) const; bool <B><A HREF="#type_info::operator!=">operator!=</A></B>(const type_info& right) const; bool <B><A HREF="#type_info::before">before</A></B>(const type_info& right) const; const char *<B><A HREF="#type_info::name">name</A></B>() const;private: <B>type_info</B>(const type_info& right); type_info& <B>operator=</B>(const type_info& right); };</PRE><P>The class describes type information generatedwithin the program by the implementation. Objects of this class effectivelystore a pointer to a<B><A NAME="names for types">name</A></B> for the type,and an encoded value suitable for comparing two types for equality or<B><A NAME="collating order for types">collating order</A></B>.The names, encoded values, and collating order for typesare all unspecified and may differ between program executions.</P><P>An expression of the form <CODE>typeid Ty</CODE> is the <I>only</I> way toconstruct a (temporary) <CODE>typeinfo</CODE> object. The class has onlya private copy constructor. Since the assignment operator is alsoprivate, you cannot copy or assign objects of class <CODE>typeinfo</CODE>either.</P><H3><A NAME="type_info::operator!="><CODE>type_info::operator!=</CODE></A></H3><PRE>bool <B>operator!=</B>(const type_info& right) const;</PRE><P>The function returns <CODE>!(*this<A HREF="#type_info::operator==">==</A> right)</CODE>.</P><H3><A NAME="type_info::operator=="><CODE>type_info::operator==</CODE></A></H3><PRE>bool <B>operator==</B>(const type_info& right) const;</PRE><P>The function returns a nonzero value if <CODE>*this</CODE>and <CODE>right</CODE> represent the same type.</P><H3><A NAME="type_info::before"><CODE>type_info::before</CODE></A></H3><PRE>bool <B>before</B>(const type_info& right) const;</PRE><P>The function returns a nonzero value if <CODE>*this</CODE>precedes <CODE>right</CODE> in the<A HREF="#collating order for types">collating order</A> for types.</P><H3><A NAME="type_info::name"><CODE>type_info::name</CODE></A></H3><PRE>const char *<B>name</B>() const;</PRE><P>The function returns a<A HREF="lib_over.html#C string">C string</A> which specifies the<A HREF="#names for types">name</A> of the type.</P><HR><P>See also the<B><A HREF="index.html#Table of Contents">Table of Contents</A></B> and the<B><A HREF="_index.html">Index</A></B>.</P><P><I><A HREF="crit_pjp.html">Copyright</A> © 1992-2002by P.J. Plauger. All rights reserved.</I></P><!--V4.01:1125--></BODY></HTML>⌨️ 快捷键说明
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