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<TITLE>Fundamental Datatypes</TITLE>
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<H2>21.2 Fundamental Datatypes</H2>
<A NAME="idx448"><!></A>
<A NAME="idx449"><!></A>
<P>The C++ Standard Library describes a specific type by providing a specialization of the<SAMP> numeric_limits</SAMP> template for the type. Static member functions and static constant data members then provide information specific to the type. The C++ Standard Library includes descriptions of the fundamental datatypes given in <A HREF="21-2.html#Table&nbsp;21">Table&nbsp;21</A>.</P>
<H4><A NAME="Table&nbsp;21">Table&nbsp;21: Fundamental datatypes of the C++ Standard Library&nbsp;</A></H4>
<TABLE BORDER="1" CELLPADDING="3" CELLSPACING="3">
<tr><td valign=top><B><SAMP>bool</SAMP></B>
</td><td valign=top><B><SAMP>char</SAMP></B>
</td><td valign=top><B><SAMP>int</SAMP></B>
</td><td valign=top><B><SAMP>float</SAMP></B>
</td></tr>
<tr><td valign=top colspan=1 rowspan=6>&nbsp;
</td><td valign=top><P CLASS="TABLE"><SAMP>signed char</SAMP></P>
</td><td valign=top><P CLASS="TABLE"><SAMP>short</SAMP></P>
</td><td valign=top><P CLASS="TABLE"><SAMP>double</SAMP></P>
</td></tr>
<tr><td valign=top><P CLASS="TABLE"><SAMP>unsigned char</SAMP></P>
</td><td valign=top><P CLASS="TABLE"><SAMP>long</SAMP></P>
</td><td valign=top><P CLASS="TABLE"><SAMP>long double</SAMP></P>
</td></tr>
<tr><td valign=top colspan=1 rowspan=4>&nbsp;
</td><td valign=top><P CLASS="TABLE"><SAMP>wchar_t</SAMP></P>
</td><td valign=top colspan=1 rowspan=4>&nbsp;
</td></tr>
<tr><td valign=top><P CLASS="TABLE"><SAMP>unsigned short</SAMP></P>
</td></tr>
<tr><td valign=top><P CLASS="TABLE"><SAMP>unsigned int</SAMP></P>
</td></tr>
<tr><td valign=top><P CLASS="TABLE"><SAMP>unsigned long</SAMP></P>
</td></tr>
</TABLE>
<P>Certain implementations may also provide information on other datatypes. Whether or not an implementation is described can be discovered using the static data member <SAMP>is_specialized</SAMP>. For example, the following is legal, and will indicate that the <B><I><A HREF="../stdlibref/basic-string.html">string</A></I></B> datatype is not described by this mechanism.</P>

<UL><PRE>
std::cout &lt;&lt; "are strings described " &lt;&lt;
   std::numeric_limits&lt;string&gt;::is_specialized &lt;&lt; std::endl;
</PRE></UL>
<P>For datatypes that do not have a specialization, the values yielded by the functions and data members in <SAMP>numeric_limits</SAMP> are generally zero or <SAMP>false</SAMP>.</P>

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