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<html>
<head>
<title>BOOST_PP_SUB_D</title>
<link rel="stylesheet" type="text/css" href="../styles.css">
</head>
<body>
<div style="margin-left: 0px;">
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.
</div>
<h4>Usage</h4>
<div class="code">
<b>BOOST_PP_SUB_D</b>(<i>d</i>, <i>x</i>, <i>y</i>)
</div>
<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>
<div>
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>.
</div>
<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>
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<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>
</body>
</html>
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