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<H2>clog</H2>
<P><B>Library:</B>&nbsp;&nbsp;<A HREF="2-11.html">Input/output</A></P><UL>
<LI><A HREF="#sec1">Local Index</A></LI>
<LI><A HREF="#sec2">Summary</A></LI>
<LI><A HREF="#sec3">Synopsis</A></LI>
<LI><A HREF="#sec4">Description</A></LI>
<LI><A HREF="#sec5">Formatting</A></LI>
<LI><A HREF="#sec6">Warnings</A></LI>
<LI><A HREF="#sec7">See Also</A></LI>
<LI><A HREF="#sec8">Standards Conformance</A></LI>
</UL>
<A NAME="sec1"><H3>Local Index</H3></A>
No Entries
<A NAME="sec2"><H3>Summary</H3></A>
<P>A predefined stream that controls output to a stream buffer associated with the object <SAMP>stderr</SAMP> declared in <SAMP>&lt;cstdio&gt;</SAMP></P>
<A NAME="sec3"><H3>Synopsis</H3></A>

<PRE>#include &lt;iostream&gt;

namespace std {
  extern ostream clog;
}
</PRE>
<A NAME="sec4"><H3>Description</H3></A>
<P>The object <SAMP>clog</SAMP> controls output to a stream buffer associated with the object <SAMP>stderr</SAMP> declared in <SAMP>&lt;cstdio&gt;</SAMP>. The difference between <SAMP>clog</SAMP> and <SAMP>cerr</SAMP> is that <SAMP>clog</SAMP> is buffered but <SAMP>cerr</SAMP> is not. Therefore, commands like <SAMP>clog</SAMP> <SAMP>&lt;&lt; "ERROR !!";</SAMP> and <SAMP>fprintf(stderr,"ERROR !!");</SAMP> are not synchronized. </P>
<A NAME="sec5"><H3>Formatting</H3></A>
<P>The formatting is done through member functions or manipulators. See <B><I><A HREF="cout.html">cout</A></I></B> or <B><I><A HREF="basic-ostream.html">basic_ostream</A></I></B> for details. </P>
<A NAME="sec6"><H3>Warnings</H3></A>
<P><SAMP>clog</SAMP> can be used to redirect some of the errors to another recipient. For example, you might want to redirect them to a file named <SAMP>my_err</SAMP>, as in: </P>

<UL><PRE>
ofstream out("my_err");
if ( out )
  clog.rdbuf(out.rdbuf());

else

  cerr &lt;&lt; "Error while opening the file" &lt;&lt; endl;
</PRE></UL>
<P>Then when you are doing something like: </P>

<UL><PRE>
clog &lt;&lt; "error number x"; 
</PRE></UL>
<P>the error message is output to the file <SAMP>my_err</SAMP>. Obviously, you can use the same scheme to redirect <SAMP>clog</SAMP> to other devices.</P>
<A NAME="sec7"><H3>See Also</H3></A>
<P><B><I><A HREF="basic-ostream.html">basic_ostream</A></I></B>, <B><I><A HREF="basic-iostream.html">basic_iostream</A></I></B>, <B><I><A HREF="basic-filebuf.html">basic_filebuf</A></I></B>, <B><I><A HREF="cout.html">cout</A></I></B>, <B><I><A HREF="cin.html">cin</A></I></B>, <B><I><A HREF="cerr.html">cerr</A></I></B>, <B><I><A HREF="wcin.html">wcin</A></I></B>, <B><I><A HREF="wcout.html">wcout</A></I></B>, <B><I><A HREF="wcerr.html">wcerr</A></I></B>, <B><I><A HREF="wclog.html">wclog</A></I></B>,  <B><I><A HREF="ios-base.html">ios_base</A></I></B>, <B><I><A HREF="basic-ios.html">basic_ios</A></I></B></P>
<A NAME="sec8"><H3>Standards Conformance</H3></A>
<P><I>ISO/IEC 14882:1998 -- International Standard for Information Systems --Programming Language C++, Section 27.3.1</I></P>

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