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<Head>
<Title>find_end</Title>
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<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 within
the range <tt>[first1, last1)</tt> that is identical to <tt>[first2, last2)</tt>.
The difference is that while <tt>search</tt> finds the first such
subsequence, <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>search</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, for
every 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, for
every iterator <tt>j</tt> in <tt>[first2, last2)</tt>,
<tt>binary_pred(*(i + (j - first2)), *j)</tt> is <tt>true</tt>. These conditions
simply 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 <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 complexity
is 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 a
subsequence 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 subsequence
unless <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 arguments
such that <tt>last1 - first1</tt> is less than <tt>last2 - first2</tt>, but such a
search will always fail.
<h3>See also</h3>
<tt><A href="search.html">search</A></tt>
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