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  3. <title>BOOST_PP_IF</title>
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  8. The <b>BOOST_PP_IF</b> macro chooses between to values based on a logical condition.
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  10. <h4>Usage</h4>
  11. <div class="code">
  12. <b>BOOST_PP_IF</b>(<i>cond</i>, <i>t</i>, <i>f</i>)
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  14. <h4>Arguments</h4>
  15. <dl>
  16. <dt>cond</dt>
  17. <dd>
  18. The condition that determines if the result is <i>expr</i> or nothing.&nbsp;
  19. Valid values range from <i>0</i> to <b>BOOST_PP_LIMIT_MAG</b>.
  20. </dd>
  21. <dt>t</dt>
  22. <dd>
  23. The result of the expansion if <i>cond</i> is non-zero.
  24. </dd>
  25. <dt>f</dt>
  26. <dd>
  27. The result of the expansion if <i>cond</i> is <i>0</i>.
  28. </dd>
  29. </dl>
  30. <h4>Remarks</h4>
  31. <div>
  32. This macro performs a boolean conversion on its first argument.&nbsp;
  33. If that conversion is unnecessary, use <b>BOOST_PP_IIF</b> instead.
  34. </div>
  35. <h4>See Also</h4>
  36. <ul>
  37. <li><a href="iif.html">BOOST_PP_IIF</a></li>
  38. <li><a href="limit_mag.html">BOOST_PP_LIMIT_MAG</a></li>
  39. </ul>
  40. <h4>Requirements</h4>
  41. <div>
  42. <b>Header:</b> &nbsp;<a href="../headers/control/if.html">&lt;boost/preprocessor/control/if.hpp&gt;</a>
  43. </div>
  44. <h4>Sample Code</h4>
  45. <div><pre>
  46. #include &lt;<a href="../headers/control/if.html">boost/preprocessor/control/if.hpp</a>&gt;
  47. <a href="if.html">BOOST_PP_IF</a>(10, a, b) // expands to a
  48. <a href="if.html">BOOST_PP_IF</a>(0, a, b) // expands to b
  49. </pre></div>
  50. <hr size="1">
  51. <div style="margin-left: 0px;">
  52. <i>© Copyright <a href="http://www.housemarque.com" target="_top">Housemarque Oy</a> 2002</i>
  53. </br><i>© Copyright Paul Mensonides 2002</i>
  54. </div>
  55. <div style="margin-left: 0px;">
  56. <p><small>Distributed under the Boost Software License, Version 1.0. (See
  57. accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or
  58. copy at <a href=
  59. "http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
  60. </div>
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