is_begin_parens.html 2.5 KB

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  4. <title>BOOST_PP_IS_BEGIN_PARENS</title>
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  8. <div style="margin-left: 0px;"> The <b>BOOST_PP_IS_BEGIN_PAREN</b>S
  9. determines whether the input starts with a set of parenthesis.</div>
  10. <h4>Usage</h4>
  11. <div class="code"> <b>BOOST_PP_IS_BEGIN_PARENS</b>(...) <a href="../topics/variadic_macros.html#VNotation"
  12. target="_self"><sup>(v)</sup></a></div>
  13. <h4>Arguments</h4>
  14. <h4>&nbsp;&nbsp;&nbsp; ...&nbsp;&nbsp;&nbsp; <span style="font-weight: normal;">&nbsp;&nbsp;&nbsp;
  15. &nbsp;&nbsp;&nbsp; The input as variadic data.</span></h4>
  16. <h4>Remarks</h4>
  17. <div> If the input input begins with a parenthesis, with any data within
  18. that parenthesis, the macro returns 1, otherwise it returns 0. Data may
  19. follow the beginning parenthesis and the macro still will return 1.<br>
  20. <br>
  21. For Visual Studio 2005 ( VC8 ) the input data must be a single parameter
  22. else a compilation error will occur.</div>
  23. <h4>See Also</h4>
  24. <ul>
  25. <li><a href="remove_parens.html">BOOST_PP_REMOVE_PARENS</a></li>
  26. </ul>
  27. <h4>Requirements</h4>
  28. <div> <b>Header:</b> &nbsp;<a href="../headers/punctuation/is_begin_parens.html">&lt;boost/preprocessor/punctuation/is_begin_parens.hpp&gt;</a>
  29. </div>
  30. <h4>Sample Code</h4>
  31. <div>
  32. <pre>#include &lt;<a href="../headers/punctuation/is_begin_parens.html">boost/preprocessor/punctuation/is_begin_parens.hpp</a>&gt;
  33. #define VARDATA more_data , more_params<br>#define VARDATAP ( data ) more_data , more_params<br>#define DATA data<br>#define DATAP ( data ) more_data<br>
  34. BOOST_PP_IS_BEGIN_PARENS(VARDATA) // expands to 0, compiler error with VC8
  35. BOOST_PP_IS_BEGIN_PARENS(VARDATAP) // expands to 1, compiler error with VC8<br><br>BOOST_PP_IS_BEGIN_PARENS(DATA) // expands to 0
  36. BOOST_PP_IS_BEGIN_PARENS(DATAP) // expands to 1<br><br>BOOST_PP_IS_BEGIN_PARENS() // expands to 0<br>
  37. </pre></div>
  38. <hr size="1">
  39. <div style="margin-left: 0px;"> <i>© Copyright Edward Diener 2014</i> </div>
  40. <div style="margin-left: 0px;">
  41. <p><small>Distributed under the Boost Software License, Version 1.0. (See
  42. accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a>
  43. or copy at <a href="http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
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