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<HTML><HEAD><TITLE>21.2 Fundamental Data Types</TITLE></HEAD><BODY><A HREF="ug1.htm"><IMG SRC="images/banner.gif"></A><BR><A HREF="ove_1724.htm"><IMG SRC="images/prev.gif"></A><A HREF="booktoc1.htm"><IMG SRC="images/toc.gif"></A><A HREF="tindex1.htm"><IMG SRC="images/tindex.gif"></A><A HREF="num_4324.htm"><IMG SRC="images/next.gif"></A><BR><STRONG>Click on the banner to return to the user guide home page.</STRONG><H2>21.2 Fundamental Data Types</H2><P>The standard library describes a specific type by providing a specialized implementation of the<SAMP> numeric_limits</SAMP> class for the type. Static functions and static constant data members then provide information specific to the type. The standard library includes descriptions of the following fundamental data types.</P><TABLE CELLSPACING=3 CELLPADDING=3><TR VALIGN=top><TD><SAMP>bool</SAMP><BR></TD><TD><SAMP>char</SAMP><BR></TD><TD><SAMP>int</SAMP><BR></TD><TD><SAMP>float</SAMP><BR></TD></TR><TR VALIGN=top><TD> </TD><TD><SAMP>signed char</SAMP><BR></TD><TD><SAMP>short</SAMP><BR></TD><TD><SAMP>double</SAMP><BR></TD></TR><TR VALIGN=top><TD> </TD><TD><SAMP>unsigned char</SAMP><BR></TD><TD><SAMP>long</SAMP><BR></TD><TD><SAMP>long double</SAMP><BR></TD></TR><TR VALIGN=top><TD> </TD><TD><SAMP>wchar_t</SAMP><BR></TD><TD><SAMP>unsigned short</SAMP><BR></TD><TD> </TD></TR><TR VALIGN=top><TD> </TD><TD> </TD><TD><SAMP>unsigned int</SAMP><BR></TD><TD> </TD></TR><TR VALIGN=top><TD> </TD><TD> </TD><TD><SAMP>unsigned long</SAMP><BR></TD><TD> </TD></TR></TABLE><P>Certain implementations may also provide information on other data types. Whether or not an implementation is described can be discovered using the static data member field<SAMP> is_specialized</SAMP>. For example, the following is legal, and will indicate that the <A HREF="../stdlibcr/str_8586.htm"><B><I>string</I></B></A> data type is not described by this mechanism.</P><PRE>cout << "are strings described " << numeric_limits<string>::is_specialized << endl;</PRE><P>For data types that do not have a specialization, the values yielded by the functions and data fields in <SAMP>numeric_limits</SAMP> are generally zero or false.</P><HR><A HREF="ove_1724.htm"><IMG SRC="images/prev.gif"></A> <A HREF="booktoc1.htm"><IMG SRC="images/toc.gif"></A><A HREF="tindex1.htm"><IMG SRC="images/tindex.gif"></A><A HREF="num_4324.htm"><IMG SRC="images/next.gif"></A><P>©Copyright 1996, Rogue Wave Software, Inc.</P></BODY></HTML>⌨️ 快捷键说明
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