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It is provided "as is" without express or implied warranty. -- --><Head><Title>stable_partition</Title><!-- Generated by htmldoc --></HEAD><BODY BGCOLOR="#ffffff" LINK="#0000ee" TEXT="#000000" VLINK="#551a8b" ALINK="#ff0000"> <IMG SRC="CorpID.gif" ALT="SGI" HEIGHT="43" WIDTH="151"> <!--end header--><BR Clear><H1>stable_partition</H1><Table CellPadding=0 CellSpacing=0 width=100%><TR><TD Align=left><Img src = "algorithms.gif" Alt="" WIDTH = "194" HEIGHT = "38" ></TD><TD Align=right><Img src = "function.gif" Alt="" WIDTH = "194" HEIGHT = "38" ></TD></TR><TR><TD Align=left VAlign=top><b>Category</b>: algorithms</TD><TD Align=right VAlign=top><b>Component type</b>: function</TD></TR></Table><h3>Prototype</h3><pre>template <class <A href="ForwardIterator.html">ForwardIterator</A>, class <A href="Predicate.html">Predicate</A>>ForwardIterator stable_partition(ForwardIterator first, ForwardIterator last, Predicate pred);</pre> <h3>Description</h3><tt>Stable_partition</tt> is much like <tt><A href="partition.html">partition</A></tt>: it reorders the elements in the range <tt>[first, last)</tt> basedon the <A href="functors.html">function object</A> <tt>pred</tt>, such that allof the elements that satisfy <tt>pred</tt> appear before all of the elementsthat fail to satisfy it. The postcondition is that, for someiterator <tt>middle</tt> in the range <tt>[first, last)</tt>, <tt>pred(*i)</tt> is <tt>true</tt> for every iterator <tt>i</tt> in the range <tt>[first, middle)</tt> and<tt>false</tt> for every iterator <tt>i</tt> in the range <tt>[middle, last)</tt>.The return value of <tt>stable_partition</tt> is <tt>middle</tt>.<P><tt>Stable_partition</tt> differs from <tt><A href="partition.html">partition</A></tt> in that<tt>stable_partition</tt> is guaranteed to preserve relative order. That is,if <tt>x</tt> and <tt>y</tt> are elements in <tt>[first, last)</tt> such that <tt>pred(x) == pred(y)</tt>,and if <tt>x</tt> precedes <tt>y</tt>, then it will still be true after <tt>stable_partition</tt>is true that <tt>x</tt> precedes <tt>y</tt>. <A href="#1">[1]</A><h3>Definition</h3>Defined in the standard header <A href="algorithm">algorithm</A>, and in the nonstandardbackward-compatibility header <A href="algo.h">algo.h</A>.<h3>Requirements on types</h3><UL><LI><tt>ForwardIterator</tt> is a model of <A href="ForwardIterator.html">Forward Iterator</A><LI><tt>Predicate</tt> is a model of <A href="Predicate.html">Predicate</A><LI><tt>ForwardIterator</tt>'s value type is convertible to <tt>Predicate</tt>'s argument type.</UL><h3>Preconditions</h3><UL><LI><tt>[first, last)</tt> is a valid range.</UL><h3>Complexity</h3><tt>Stable_partition</tt> is an <i>adaptive</i> algorithm: it attempts toallocate a temporary memory buffer, and its run-time complexity dependson how much memory is available. Worst-case behavior (if no auxiliary memory is available) is at most <tt>N*log(N)</tt> swaps, where <tt>N</tt> is <tt>last - first</tt>, and best case (if a large enough auxiliary memory buffer is available) is linear in <tt>N</tt>. In either case, <tt>pred</tt> is applied exactly <tt>N</tt> times.<h3>Example</h3>Reorder a sequence so that even numbers precede odd numbers.<pre>int A[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};const int N = sizeof(A)/sizeof(int);stable_partition(A, A + N, <A href="unary_compose.html">compose1</A>(<A href="binder2nd.html">bind2nd</A>(<A href="equal_to.html">equal_to</A><int>(), 0), <A href="binder2nd.html">bind2nd</A>(<A href="modulus.html">modulus</A><int>(), 2)));<A href="copy.html">copy</A>(A, A + N, <A href="ostream_iterator.html">ostream_iterator</A><int>(cout, " "));// The output is "2 4 6 8 10 1 3 5 7 9". <A href="#1">[1]</A></pre><h3>Notes</h3><P><A name="1">[1]</A>Note that the complexity of <tt>stable_partition</tt> is greater thanthat of <tt><A href="partition.html">partition</A></tt>: the guarantee that relative order will be preservedhas a significant runtime cost. If this guarantee isn't important toyou, you should use <tt><A href="partition.html">partition</A></tt>.<h3>See also</h3><tt><A href="partition.html">partition</A></tt>, <A href="Predicate.html">Predicate</A>, <A href="functors.html">function object</A><!--start footer--> <HR SIZE="6"><A href="http://www.sgi.com/"><IMG SRC="surf.gif" HEIGHT="54" WIDTH="54" ALT="[Silicon Surf]"></A><A HREF="index.html"><IMG SRC="stl_home.gif" HEIGHT="54" WIDTH="54" ALT="[STL Home]"></A><BR><FONT SIZE="-2"><A href="http://www.sgi.com/Misc/sgi_info.html" TARGET="_top">Copyright © 1999 Silicon Graphics, Inc.</A> All Rights Reserved.</FONT><FONT SIZE="-3"><a href="http://www.sgi.com/Misc/external.list.html" TARGET="_top">TrademarkInformation</A></FONT><P></BODY></HTML> ⌨️ 快捷键说明
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