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| <title>BOOST_PP_SUB_D</title> |
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| The <b>BOOST_PP_SUB_D</b> macro expands to the difference between its second and third arguments. |
| It reenters <b>BOOST_PP_WHILE</b> with maximum efficiency. |
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| <h4>Usage</h4> |
| <div class="code"> |
| <b>BOOST_PP_SUB_D</b>(<i>d</i>, <i>x</i>, <i>y</i>) |
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| <h4>Arguments</h4> |
| <dl> |
| <dt>d</dt> |
| <dd> |
| The next available <b>BOOST_PP_WHILE</b> iteration. |
| </dd> |
| <dt>x</dt> |
| <dd> |
| The minuend of the operation. |
| Valid values range from <i>0</i> to <b>BOOST_PP_LIMIT_MAG</b>. |
| </dd> |
| <dt>y</dt> |
| <dd> |
| The subtrahend of the operation. |
| Valid values range from <i>0</i> to <b>BOOST_PP_LIMIT_MAG</b>. |
| </dd> |
| </dl> |
| <h4>Remarks</h4> |
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| If the difference between <i>x</i> and <i>y</i> is less than <i>0</i>, the result is saturated to <i>0</i>. |
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| <h4>See Also</h4> |
| <ul> |
| <li><a href="limit_mag.html">BOOST_PP_LIMIT_MAG</a></li> |
| <li><a href="sub.html">BOOST_PP_SUB</a></li> |
| </ul> |
| <h4>Requirements</h4> |
| <div> |
| <b>Header:</b> <a href="../headers/arithmetic/sub.html"><boost/preprocessor/arithmetic/sub.hpp></a> |
| </div> |
| <h4>Sample Code</h4> |
| <div><pre> |
| #include <<a href="../headers/arithmetic/dec.html">boost/preprocessor/arithmetic/dec.hpp</a>> |
| #include <<a href="../headers/arithmetic/sub.html">boost/preprocessor/arithmetic/sub.hpp</a>> |
| #include <<a href="../headers/control/while.html">boost/preprocessor/control/while.hpp</a>> |
| #include <<a href="../headers/tuple/elem.html">boost/preprocessor/tuple/elem.hpp</a>> |
| |
| #define PRED(d, data) <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(2, 0, data) |
| |
| #define OP(d, data) \ |
| ( \ |
| <a href="dec.html">BOOST_PP_DEC</a>( \ |
| <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(2, 0, data) \ |
| ), \ |
| <a href="sub_d.html">BOOST_PP_SUB_D</a>( \ |
| d, \ |
| <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(2, 1, data), \ |
| 2 \ |
| ) \ |
| ) \ |
| /**/ |
| |
| // decrement 'x' by 2 'n' times |
| #define STRIDE(x, n) <a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(2, 1, <a href="while.html">BOOST_PP_WHILE</a>(PRED, OP, (n, x))) |
| |
| STRIDE(10, 2) // expands to 6 |
| STRIDE(14, 6) // expands to 2 |
| </pre></div> |
| <hr size="1"> |
| <div style="margin-left: 0px;"> |
| <i>© Copyright <a href="http://www.housemarque.com" target="_top">Housemarque Oy</a> 2002</i> |
| </br><i>© Copyright Paul Mensonides 2002</i> |
| </div> |
| <div style="margin-left: 0px;"> |
| <p><small>Distributed under the Boost Software License, Version 1.0. (See |
| accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or |
| copy at <a href= |
| "http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p> |
| </div> |
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