projects / ceph.git / blame
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|---|---|---|
| 7c673cae FG |
1 | <html> |
| 2 | <head> | |
| 3 | <title>BOOST_PP_EXPR_IIF</title> | |
| 4 | <link rel="stylesheet" type="text/css" href="../styles.css"> | |
| 5 | </head> | |
| 6 | <body> | |
| 7 | <div style="margin-left: 0px;"> | |
| 8 | The <b>BOOST_PP_EXPR_IIF</b> macro expands to its second argument if its first argument is <i>1</i> and expands to nothing if its first argument is <i>0</i>. | |
| 9 | </div> | |
| 10 | <h4>Usage</h4> | |
| 11 | <div class="code"> | |
| 12 | <b>BOOST_PP_EXPR_IIF</b>(<i>bit</i>, <i>expr</i>) | |
| 13 | </div> | |
| 14 | <h4>Arguments</h4> | |
| 15 | <dl> | |
| 16 | <dt>bit</dt> | |
| 17 | <dd> | |
| 18 | The condition that determines if the result is <i>expr</i> or nothing. | |
| 19 | This value must expand to <i>0</i> or </i>1</i>. | |
| 20 | </dd> | |
| 21 | <dt>expr</dt> | |
| 22 | <dd> | |
| 23 | The result of the expansion if <i>bit</i> is <i>1</i>. | |
| 24 | </dd> | |
| 25 | </dl> | |
| 26 | <h4>Remarks</h4> | |
| 27 | <div> | |
| 28 | This macro <i>does not</i> perform a boolean conversion on its first argument. | |
| 29 | If that conversion is necessary, use <b>BOOST_PP_EXPR_IF</b> instead. | |
| 30 | </div> | |
| 31 | <h4>See Also</h4> | |
| 32 | <ul> | |
| 33 | <li><a href="expr_if.html">BOOST_PP_EXPR_IF</a></li> | |
| 34 | <li><a href="limit_mag.html">BOOST_PP_LIMIT_MAG</a></li> | |
| 35 | </ul> | |
| 36 | <h4>Requirements</h4> | |
| 37 | <div> | |
| 38 | <b>Header:</b> <a href="../headers/control/expr_iif.html"><boost/preprocessor/control/expr_iif.hpp></a> | |
| 39 | </div> | |
| 40 | <h4>Sample Code</h4> | |
| 41 | <div><pre> | |
| 42 | #include <<a href="../headers/logical/and.html">boost/preprocessor/logical/and.hpp</a>> | |
| 43 | #include <<a href="../headers/control/expr_iif.html">boost/preprocessor/control/expr_iif.hpp</a>> | |
| 44 | ||
| 45 | #define INSERT_AND(p, q, text) \ | |
| 46 | <a href="expr_iif.html">BOOST_PP_EXPR_IIF</a>( \ | |
| 47 | <a href="and.html">BOOST_PP_AND</a>(p, q), \ | |
| 48 | text \ | |
| 49 | ) \ | |
| 50 | /**/ | |
| 51 | ||
| 52 | INSERT_AND(2, 3, abc) // expands to abc | |
| 53 | INSERT_AND(0, 7, xyz) // expands to nothing | |
| 54 | </pre></div> | |
| 55 | <hr size="1"> | |
| 56 | <div style="margin-left: 0px;"> | |
| 57 |