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It is provided "as is" without express or implied warranty. -- --><Head><Title>unique_copy</Title><!-- Generated by htmldoc --></HEAD><BODY TEXT="#000000" LINK="#006600" ALINK="#003300" VLINK="#7C7F87" BGCOLOR="#FFFFFF"><A HREF="/"><IMG SRC="/images/common/sgilogo_small.gif" ALT="SGI Logo" WIDTH="80" HEIGHT="72" BORDER="0"></A><P><!--end header--><BR Clear><H1>unique_copy</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>Unique_copy</tt> is an overloaded name; there areactually two <tt>unique_copy</tt> functions.<pre>template <class <A href="InputIterator.html">InputIterator</A>, class <A href="OutputIterator.html">OutputIterator</A>>OutputIterator unique_copy(InputIterator first, InputIterator last, OutputIterator result);template <class <A href="InputIterator.html">InputIterator</A>, class <A href="OutputIterator.html">OutputIterator</A>, class <A href="BinaryPredicate.html">BinaryPredicate</A>>OutputIterator unique_copy(InputIterator first, InputIterator last, OutputIterator result, BinaryPredicate binary_pred);</pre> <h3>Description</h3><tt>Unique_copy</tt> copies elements from the range <tt>[first, last)</tt> to a range beginning with <tt>result</tt>, except that in a consecutive group of duplicate elements only the first one is copied. The return value isthe end of the range to which the elements are copied. This behavior is similar to the Unix filter <tt>uniq</tt>.<P>The reason there are two different versions of <tt>unique_copy</tt> is that thereare two different definitions of what it means for a consecutive groupof elements to be duplicates. In the first version, the test issimple equality: the elements in a range <tt>[f, l)</tt> are duplicates if,for every iterator <tt>i</tt> in the range, either <tt>i == f</tt> or else <tt>*i == *(i-1)</tt>.In the second, the test is an arbitrary <A href="BinaryPredicate.html">Binary Predicate</A><tt>binary_pred</tt>: the elements in <tt>[f, l)</tt> are duplicates if, for every iterator <tt>i</tt> in the range, either <tt>i == f</tt> or else<tt>binary_pred(*i, *(i-1))</tt> is <tt>true</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>For the first version:<UL><LI><tt>InputIterator</tt> is a model of <A href="InputIterator.html">Input Iterator</A>.<LI><tt>InputIterator</tt>'s value type is <A href="EqualityComparable.html">Equality Comparable</A>.<LI><tt>OutputIterator</tt> is a model of <A href="OutputIterator.html">Output Iterator</A>.<LI><tt>InputIterator</tt>'s value type is convertible to a type in <tt>OutputIterator</tt>'s set of value types.</UL>For the second version:<UL><LI><tt>InputIterator</tt> is a model of <A href="InputIterator.html">Input Iterator</A>.<LI><tt>BinaryPredicate</tt> is a model of <A href="BinaryPredicate.html">Binary Predicate</A>. <A href="#2">[2]</A><LI><tt>InputIterator</tt>'s value type is convertible to first argument type and to <tt>BinaryPredicate</tt>'s second argument type.<LI><tt>OutputIterator</tt> is a model of <A href="OutputIterator.html">Output Iterator</A>.<LI><tt>InputIterator</tt>'s value type is convertible to a type in <tt>OutputIterator</tt>'s set of value types.</UL><h3>Preconditions</h3><UL><LI><tt>[first, last)</tt> is a valid range.<LI>There is enough space to hold all of the elements being copied. More formally, if there are <tt>n</tt> elements in the range <tt>[first, last)</tt> after duplicates are removed from consecutive groups, then <tt>[result, result + n)</tt> must be a valid range.</UL><h3>Complexity</h3>Linear. Exactly <tt>last - first</tt> applications of <tt>operator==</tt>(in the case of the first version of <tt>unique</tt>) or of <tt>binary_pred</tt>(in the case of the second version), and at most <tt>last - first</tt>assignments.<h3>Example</h3>Print all of the numbers in an array, but only print the first onein a consecutive group of identical numbers.<pre>const int A[] = {2, 7, 7, 7, 1, 1, 8, 8, 8, 2, 8, 8};unique_copy(A, A + sizeof(A) / sizeof(int), <A href="ostream_iterator.html">ostream_iterator</A><int>(cout, " "));// The output is "2 7 1 8 2 8".</pre><h3>Notes</h3><P><A name="1">[1]</A>Strictly speaking, the first version of <tt>unique_copy</tt> is redundant:you can achieve the same functionality by using an object of class<tt><A href="equal_to.html">equal_to</A></tt> as the <A href="BinaryPredicate.html">Binary Predicate</A> argument. The first versionis provided strictly for the sake of convenience: testing for equalityis an important special case.<P><A name="2">[2]</A><tt>BinaryPredicate</tt> is not required to be an equivalencerelation. You should be cautious, though, about using <tt>unique_copy</tt> with a<A href="BinaryPredicate.html">Binary Predicate</A> that is not an equivalence relation: you couldeasily get unexpected results.<h3>See also</h3><A href="BinaryPredicate.html">Binary Predicate</A>, <tt><A href="unique.html">unique</A></tt>, <tt><A href="remove_copy.html">remove_copy</A></tt>, <tt><A href="remove_copy_if.html">remove_copy_if</A></tt>,<tt><A href="adjacent_find.html">adjacent_find</A></tt><!-- start footer --><!-- Footer Begins --><STYLE TYPE="text/css"><!--TD.footer, TD.footer A{ font-family: Arial, helvetica, sans-serif; font-size: 8pt;}A.home {font-family: Arial, helvetica, sans-serif;}--></STYLE><P><A CLASS="home" HREF="index.html">STL Home</A><P><TABLE WIDTH="600" CELLPADDING="0" CELLPADDING="0" BORDER="0"> <TR> <TD ALIGN="RIGHT" CLASS="footer"><A HREF="/company_info/terms.html" TARGET="_top">terms of use</A> | <A HREF="/company_info/privacy.html" TARGET="_top">privacy policy</A></TD> <TD ALIGN="CENTER" CLASS="footer"> | </TD> <TD ALIGN="LEFT" CLASS="footer"><A HREF="/cgi-bin/feedback/" TARGET="_top">contact us</A></TD> </TR><TR> <TD ALIGN="RIGHT" CLASS="footer">Copyright © 1993-2003 Silicon Graphics, Inc. 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