📄 find_end.html
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<HTML><!-- -- Copyright (c) 1996-1999 -- Silicon Graphics Computer Systems, Inc. -- -- Permission to use, copy, modify, distribute and sell this software -- and its documentation for any purpose is hereby granted without fee, -- provided that the above copyright notice appears in all copies and -- that both that copyright notice and this permission notice appear -- in supporting documentation. Silicon Graphics makes no -- representations about the suitability of this software for any -- purpose. It is provided "as is" without express or implied warranty. -- -- Copyright (c) 1994 -- Hewlett-Packard Company -- -- Permission to use, copy, modify, distribute and sell this software -- and its documentation for any purpose is hereby granted without fee, -- provided that the above copyright notice appears in all copies and -- that both that copyright notice and this permission notice appear -- in supporting documentation. 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It is provided "as is" without express or implied warranty. -- --><Head><Title>find_end</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>find_end</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><tt>find_end</tt> is an overloaded name; there are actually two <tt>find_end</tt>functions.<pre>template <class ForwardIterator1, class ForwardIterator2>ForwardIterator1 find_end(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, ForwardIterator2 last2);template <class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>ForwardIterator1 find_end(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2, ForwardIterator2 last2, BinaryPredicate comp);</pre> <h3>Description</h3><tt>Find_end</tt> is misnamed: it is much more similar to <tt><A href="search.html">search</A></tt>than to <tt><A href="find.html">find</A></tt>, and a more accurate name would have been<tt>search_end</tt>.<P>Like <tt>search</tt>, <tt>find_end</tt> attempts to find a subsequence withinthe range <tt>[first1, last1)</tt> that is identical to <tt>[first2, last2)</tt>.The difference is that while <tt>search</tt> finds the first suchsubsequence, <tt>find_end</tt> finds the last such subsequence. <tt>Find_end</tt> returns an iterator pointing to the beginning of that subsequence; if no such subsequence exists, it returns <tt>last1</tt>.<P>The two versions of <tt>find_end</tt> differ in how they determine whether two elements are the same:the first uses <tt>operator==</tt>, and the second uses the user-supplied<A href="functors.html">function object</A> <tt>comp</tt>.<P>The first version of <tt>find_end</tt> returns the last iterator<tt>i</tt> in the range <tt>[first1, last1 - (last2 - first2))</tt> such that, forevery iterator <tt>j</tt> in the range <tt>[first2, last2)</tt>, <tt>*(i + (j - first2)) == *j</tt>. The second version of <tt>find_end</tt> returns the last iterator<tt>i</tt> in <tt>[first1, last1 - (last2 - first2))</tt> such that, forevery iterator <tt>j</tt> in <tt>[first2, last2)</tt>, <tt>binary_pred(*(i + (j - first2)), *j)</tt> is <tt>true</tt>. These conditionssimply mean that every element in the subrange beginning with <tt>i</tt>must be the same as the corresponding element in <tt>[first2, last2)</tt>.<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>For the first version:<UL><LI><tt>ForwardIterator1</tt> is a model of <A href="ForwardIterator.html">Forward Iterator</A>.<LI><tt>ForwardIterator2</tt> is a model of <A href="ForwardIterator.html">Forward Iterator</A>.<LI><tt>ForwardIterator1</tt>'s value type is a model of <A href="EqualityComparable.html">EqualityComparable</A>.<LI><tt>ForwardIterator2</tt>'s value type is a model of <A href="EqualityComparable.html">EqualityComparable</A>.<LI>Objects of <tt>ForwardIterator1</tt>'s value type can be compared for equality with Objects of <tt>ForwardIterator2</tt>'s value type.</UL>For the second version:<UL><LI><tt>ForwardIterator1</tt> is a model of <A href="ForwardIterator.html">Forward Iterator</A>.<LI><tt>ForwardIterator2</tt> is a model of <A href="ForwardIterator.html">Forward Iterator</A>.<LI><tt>BinaryPredicate</tt> is a model of <A href="BinaryPredicate.html">Binary Predicate</A>.<LI><tt>ForwardIterator1</tt>'s value type is convertible to <tt>BinaryPredicate</tt>'s first argument type.<LI><tt>ForwardIterator2</tt>'s value type is convertible to <tt>BinaryPredicate</tt>'s second argument type.</UL><h3>Preconditions</h3><UL><LI><tt>[first1, last1)</tt> is a valid range.<LI><tt>[first2, last2)</tt> is a valid range.</UL><h3>Complexity</h3>The number of comparisons is proportional to <tt>(last1 - first1) *(last2 - first2)</tt>. If both <tt>ForwardIterator1</tt> and <tt>ForwardIterator2</tt>are models of <A href="BidirectionalIterator.html">Bidirectional Iterator</A>, then the average complexityis linear and the worst case is at most <tt>(last1 - first1) *(last2 - first2)</tt> comparisons.<h3>Example</h3><pre>int main(){ char* s = "executable.exe"; char* suffix = "exe"; const int N = strlen(s); const int N_suf = strlen(suffix); char* location = find_end(s, s + N, suffix, suffix + N_suf); if (location != s + N) { cout << "Found a match for " << suffix << " within " << s << endl; cout << s << endl; int i; for (i = 0; i < (location - s); ++i) cout << ' '; for (i = 0; i < N_suf; ++i) cout << '^'; cout << endl; } else cout << "No match for " << suffix << " within " << s << endl;}</pre><h3>Notes</h3><P><A name="1">[1]</A>The reason that this range is <tt>[first1, last1 - (last2 - first2))</tt>,instead of simply <tt>[first1, last1)</tt>, is that we are looking for asubsequence that is equal to the <i>complete</i> sequence <tt>[first2,last2)</tt>. An iterator <tt>i</tt> can't be the beginning of such a subsequenceunless <tt>last1 - i</tt> is greater than or equal to <tt>last2 - first2</tt>.Note the implication of this: you may call <tt>find_end</tt> with argumentssuch that <tt>last1 - first1</tt> is less than <tt>last2 - first2</tt>, but such asearch will always fail.<h3>See also</h3><tt><A href="search.html">search</A></tt><!--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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