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97 lines
3.3 KiB
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97 lines
3.3 KiB
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<a href="../index.htm"><IMG height=86
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alt="c++boost.gif (8819 bytes)"
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src="../../../../c++boost.gif"
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width=277 align=center></a>
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<hr>
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<!-- Generated by Doxygen 1.2.12 -->
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<center>
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<a class="qindex" href="index.html">Main Page</a> <a class="qindex" href="files.html">File List</a> <a class="qindex" href="globals.html">File Members</a> </center>
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<hr><h1>cat.hpp File Reference</h1><table border=0 cellpadding=0 cellspacing=0>
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<tr><td colspan=2><br><h2>Defines</h2></td></tr>
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<tr><td nowrap align=right valign=top>#define </td><td valign=bottom><a class="el" href="cat_8hpp.html#a0">BOOST_PREPROCESSOR_CAT</a>(L, R)</td></tr>
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<tr><td> </td><td><font size=-1><em>Delays the catenation of L and R.</em> <a href="#a0">More...</a><em></em></font><br><br></td></tr>
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</table>
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<hr><a name="_details"></a><h2>Detailed Description</h2>
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<a href="../../../../boost/preprocessor/cat.hpp">Click here to see the header.</a>
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<p>
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<hr><h2>Define Documentation</h2>
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<a name="a0" doxytag="cat.hpp::BOOST_PREPROCESSOR_CAT"></a><p>
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<table width="100%" cellpadding="2" cellspacing="0" border="0">
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<tr>
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<td class="md">
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<table cellpadding="0" cellspacing="0" border="0">
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<tr>
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<td class="md" nowrap valign="top"> #define BOOST_PREPROCESSOR_CAT</td>
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<td class="md" valign="top">( </td>
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<td class="md" nowrap valign="top">L, <tr>
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<td></td>
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<td></td>
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<td class="md" nowrap>R </td>
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<td class="mdname1" valign="top" nowrap> </td>
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<td class="md" valign="top">) </td>
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<td class="md" nowrap>
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</table>
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</td>
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</tr>
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</table>
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<table cellspacing=5 cellpadding=0 border=0>
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<tr>
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<td>
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</td>
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<td>
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<p>
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Delays the catenation of L and R.
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<p>
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Example:
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<p>
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<pre><div class="fragment"><pre>
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#define STATIC_ASSERT(EXPR)\
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enum\
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{ BOOST_PREPROCESSOR_CAT(static_check_,__LINE__) = (EXPR) ? 1 : -1\
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};\
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typedef char\
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BOOST_PREPROCESSOR_CAT(static_assert_,__LINE__)\
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[ BOOST_PREPROCESSOR_CAT(static_check_,__LINE__)\
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]
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// ...
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STATIC_ASSERT(sizeof(int) <= sizeof(long));
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</pre></div></pre>
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<p>
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The above expands to:
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<p>
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<pre><div class="fragment"><pre>
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enum
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{ static_check_152 = (sizeof(int) <= sizeof(long)) ? 1 : -1
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};
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typedef char
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static_assert_152
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[ static_check_152
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];
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</pre></div></pre>
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<p>
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Using <a class="el" href="cat_8hpp.html#a0">BOOST_PREPROCESSOR_CAT</a>() above lets the preprocessor expand the __LINE__. If the above code would use the ## operator directly then __LINE__ would not be expanded and the above would expand to:
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<p>
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<pre><div class="fragment"><pre>
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enum
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{ static_check___LINE__ = (sizeof(int) <= sizeof(long)) ? 1 : -1
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};
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typedef char
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static_assert___LINE__
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[ static_check___LINE__
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];
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</pre></div></pre> </td>
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</tr>
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</table>
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<hr>
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<p><EFBFBD> Copyright Housemarque, Inc. 2001</p>
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<p>Permission to copy, use, modify, sell and distribute this document is granted
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provided this copyright notice appears in all copies. This document is provided
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"as is" without express or implied warranty, and with no claim as to its suitability
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for any purpose. </p>
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<p>Generated: <!--webbot bot="Timestamp" s-type="EDITED" s-format="%d %b %Y" startspan --><!--webbot bot="Timestamp" endspan i-checksum="15246" --></p>
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