doc/stdlibref/equal-range.html - stdcxx - Git at Google

 <HTML>
 <HEAD>
 <TITLE>equal_range()</TITLE>
 <LINK REL=StyleSheet HREF="../rw.css" TYPE="text/css" TITLE="Apache stdcxx Stylesheet"></HEAD>
 <BODY BGCOLOR=#FFFFFF>
 <A HREF="equal.html"><IMG SRC="images/bprev.gif" WIDTH=20 HEIGHT=21 ALT="Previous file" BORDER=O></A><A HREF="noframes.html"><IMG SRC="images/btop.gif" WIDTH=56 HEIGHT=21 ALT="Top of Document" BORDER=O></A><A HREF="booktoc.html"><IMG SRC="images/btoc.gif" WIDTH=56 HEIGHT=21 ALT="Contents" BORDER=O></A><A HREF="tindex.html"><IMG SRC="images/bindex.gif" WIDTH=56 HEIGHT=21 ALT="Index page" BORDER=O></A><A HREF="equal-to.html"><IMG SRC="images/bnext.gif" WIDTH=25 HEIGHT=21 ALT="Next file" BORDER=O></A><DIV CLASS="DOCUMENTNAME"><B>Apache C++ Standard Library Reference Guide</B></DIV>
 <H2>equal_range()</H2>
 <P><B>Library:</B>&nbsp;&nbsp;<A HREF="2-9.html">Algorithms</A></P>

 <PRE><HR><B><I>Function</I></B><HR></PRE>

 <UL>
 <LI><A HREF="#sec1">Local Index</A></LI>
 <LI><A HREF="#sec2">Summary</A></LI>
 <LI><A HREF="#sec3">Synopsis</A></LI>
 <LI><A HREF="#sec4">Description</A></LI>
 <LI><A HREF="#sec5">Complexity</A></LI>
 <LI><A HREF="#sec6">Example</A></LI>
 <LI><A HREF="#sec7">See Also</A></LI>
 <LI><A HREF="#sec8">Standards Conformance</A></LI>
 </UL>
 <A NAME="sec1"><H3>Local Index</H3></A>
 No Entries
 <A NAME="sec2"><H3>Summary</H3></A>
 <P>Algorithm that finds the largest subrange in a range of values into which a given value can be inserted without violating the ordering of the values</P>
 <A NAME="sec3"><H3>Synopsis</H3></A>

 <PRE>#include &lt;algorithm&gt;

 namespace std {
   template &lt;class ForwardIterator, class T&gt;
   pair&lt;ForwardIterator, ForwardIterator&gt;
   equal_range(ForwardIterator start, ForwardIterator finish,
               const T&amp; value);

   template &lt;class ForwardIterator, class T, class Compare&gt;
   pair&lt;ForwardIterator, ForwardIterator&gt;
   equal_range(ForwardIterator start, ForwardIterator finish,
               const T&amp; value, Compare comp);
 }
 </PRE>
 <A NAME="sec4"><H3>Description</H3></A>
 <P>The <SAMP>equal_range()</SAMP> algorithm performs a binary search on an ordered range to determine where the element <SAMP>value</SAMP> can be inserted without violating the range's ordering. The library includes two versions of the algorithm. The first version uses <SAMP>operator&lt;()</SAMP> to search for the valid insertion range, and assumes that the sequence was sorted using the same ordering. The second version allows you to specify a function object of type <SAMP>Compare</SAMP>, and assumes that <SAMP>Compare</SAMP> was the function used to sort the sequence. The function object must be a binary predicate. </P>
 <P><SAMP>equal_range()</SAMP> returns a pair of iterators, <SAMP>i</SAMP> and <SAMP>j</SAMP>, that define a range containing elements equivalent to <SAMP>value</SAMP>, in other words, the first and last valid insertion points for <SAMP>value</SAMP>. If <SAMP>value</SAMP> is not an element in the container, <SAMP>i</SAMP> and <SAMP>j</SAMP> are equal. Otherwise, <SAMP>i</SAMP> points to the first element not "less" than <SAMP>value</SAMP>, and <SAMP>j</SAMP> points to the first element greater than value. In the second version, the ordering is defined by the comparison object. Formally, <SAMP>equal_range()</SAMP> returns a sub-range <SAMP>[i, j)</SAMP> such that <SAMP>value</SAMP> can be inserted at any iterator <SAMP>k</SAMP> within the range without violating the ordering. Depending upon the version of the algorithm used, <SAMP>k</SAMP> must satisfy one of the following conditions: </P>
 <P><SAMP>!(*k &lt;  value)  &amp;&amp;  !(value  &lt;  *k)</SAMP></P>
 <P> or </P>
 <P><SAMP>comp(*k,value) == false &amp;&amp; comp(value, *k) == false</SAMP></P>
 <P>The range <SAMP>[start,finish)</SAMP> is assumed to be sorted. Type <SAMP>T</SAMP> must be LessThanComparable.</P>
 <A NAME="sec5"><H3>Complexity</H3></A>
 <P><SAMP>equal_range()</SAMP> performs at most <SAMP>2 * log(finish - start) + 1</SAMP> comparisons.</P>
 <A NAME="sec6"><H3>Example</H3></A>

 <UL><PRE>//
 // eqlrange.cpp
 //

 #include &lt;algorithm&gt;
 #include &lt;functional&gt;
 #include &lt;iostream&gt;
 #include &lt;vector&gt;


 int main ()
 {
     // Typedef for convenience.
     typedef std::vector&lt;int, std::allocator&lt;int&gt; &gt; vector;

     vector::value_type arr[] = {
         0, 1, 2, 2, 3, 4, 2, 2, 2, 6, 7
     };

     // Set up a vector.
     vector v1 (arr, arr + sizeof arr / sizeof *arr);

     // Try equal_range variants.
     std::pair&lt;vector::iterator, vector::iterator&gt; p1 =
         std::equal_range (v1.begin (), v1.end (), 3);

     std::pair&lt;vector::iterator, vector::iterator&gt; p2 =
         std::equal_range (v1.begin (), v1.end (), 2,
                      std::less&lt;vector::value_type&gt; ());

     // Output results.
     std::cout &lt;&lt; "\nThe equal range for 3 is: "
               &lt;&lt; "(" &lt;&lt; *p1.first &lt;&lt; " , "
               &lt;&lt; *p1.second &lt;&lt; ")" &lt;&lt; std::endl;

     std::cout &lt;&lt; "\nThe equal range for 2 is: "
               &lt;&lt; "(" &lt;&lt; *p2.first &lt;&lt; " , "
               &lt;&lt; *p2.second &lt;&lt; ")" &lt;&lt; std::endl;

     return 0;
 }


 Program Output
 </PRE></UL>
 <UL><PRE>
 The equal range for 3 is: (3 , 4)

 The equal range for 2 is: (2 , 3)
 </PRE></UL>
 <A NAME="sec7"><H3>See Also</H3></A>
 <P><B><I><A HREF="binary-function.html">binary_function</A></I></B>, <SAMP><A HREF="lower-bound.html">lower_bound()</A></SAMP>, <SAMP><A HREF="upper-bound.html">upper_bound()</A></SAMP></P>
 <A NAME="sec8"><H3>Standards Conformance</H3></A>
 <P><I>ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 25.3.3.3</I></P>

 <BR>
 <HR>
 <A HREF="equal.html"><IMG SRC="images/bprev.gif" WIDTH=20 HEIGHT=21 ALT="Previous file" BORDER=O></A><A HREF="noframes.html"><IMG SRC="images/btop.gif" WIDTH=56 HEIGHT=21 ALT="Top of Document" BORDER=O></A><A HREF="booktoc.html"><IMG SRC="images/btoc.gif" WIDTH=56 HEIGHT=21 ALT="Contents" BORDER=O></A><A HREF="tindex.html"><IMG SRC="images/bindex.gif" WIDTH=56 HEIGHT=21 ALT="Index page" BORDER=O></A><A HREF="equal-to.html"><IMG SRC="images/bnext.gif" WIDTH=20 HEIGHT=21 ALT="Next file" BORDER=O></A>

 <!-- Google Analytics tracking code -->
 <script src="http://www.google-analytics.com/urchin.js" type="text/javascript">
 </script>
 <script type="text/javascript">
     _uacct = "UA-1775151-1";
     urchinTracker();
 </script>
 <!-- end of Google Analytics tracking code -->

 </BODY>
 </HTML>
	<HTML>
	<HEAD>
	<TITLE>equal_range()</TITLE>
	<LINK REL=StyleSheet HREF="../rw.css" TYPE="text/css" TITLE="Apache stdcxx Stylesheet"></HEAD>
	<BODY BGCOLOR=#FFFFFF>
	<A HREF="equal.html"><IMG SRC="images/bprev.gif" WIDTH=20 HEIGHT=21 ALT="Previous file" BORDER=O></A><A HREF="noframes.html"><IMG SRC="images/btop.gif" WIDTH=56 HEIGHT=21 ALT="Top of Document" BORDER=O></A><A HREF="booktoc.html"><IMG SRC="images/btoc.gif" WIDTH=56 HEIGHT=21 ALT="Contents" BORDER=O></A><A HREF="tindex.html"><IMG SRC="images/bindex.gif" WIDTH=56 HEIGHT=21 ALT="Index page" BORDER=O></A><A HREF="equal-to.html"><IMG SRC="images/bnext.gif" WIDTH=25 HEIGHT=21 ALT="Next file" BORDER=O></A><DIV CLASS="DOCUMENTNAME"><B>Apache C++ Standard Library Reference Guide</B></DIV>
	<H2>equal_range()</H2>
	<P><B>Library:</B>  <A HREF="2-9.html">Algorithms</A></P>

	<PRE><HR><B><I>Function</I></B><HR></PRE>

	<UL>
	<LI><A HREF="#sec1">Local Index</A></LI>
	<LI><A HREF="#sec2">Summary</A></LI>
	<LI><A HREF="#sec3">Synopsis</A></LI>
	<LI><A HREF="#sec4">Description</A></LI>
	<LI><A HREF="#sec5">Complexity</A></LI>
	<LI><A HREF="#sec6">Example</A></LI>
	<LI><A HREF="#sec7">See Also</A></LI>
	<LI><A HREF="#sec8">Standards Conformance</A></LI>
	</UL>
	<A NAME="sec1"><H3>Local Index</H3></A>
	No Entries
	<A NAME="sec2"><H3>Summary</H3></A>
	<P>Algorithm that finds the largest subrange in a range of values into which a given value can be inserted without violating the ordering of the values</P>
	<A NAME="sec3"><H3>Synopsis</H3></A>

	<PRE>#include <algorithm>

	namespace std {
	template <class ForwardIterator, class T>
	pair<ForwardIterator, ForwardIterator>
	equal_range(ForwardIterator start, ForwardIterator finish,
	const T& value);

	template <class ForwardIterator, class T, class Compare>
	pair<ForwardIterator, ForwardIterator>
	equal_range(ForwardIterator start, ForwardIterator finish,
	const T& value, Compare comp);
	}
	</PRE>
	<A NAME="sec4"><H3>Description</H3></A>
	<P>The <SAMP>equal_range()</SAMP> algorithm performs a binary search on an ordered range to determine where the element <SAMP>value</SAMP> can be inserted without violating the range's ordering. The library includes two versions of the algorithm. The first version uses <SAMP>operator<()</SAMP> to search for the valid insertion range, and assumes that the sequence was sorted using the same ordering. The second version allows you to specify a function object of type <SAMP>Compare</SAMP>, and assumes that <SAMP>Compare</SAMP> was the function used to sort the sequence. The function object must be a binary predicate. </P>
	<P><SAMP>equal_range()</SAMP> returns a pair of iterators, <SAMP>i</SAMP> and <SAMP>j</SAMP>, that define a range containing elements equivalent to <SAMP>value</SAMP>, in other words, the first and last valid insertion points for <SAMP>value</SAMP>. If <SAMP>value</SAMP> is not an element in the container, <SAMP>i</SAMP> and <SAMP>j</SAMP> are equal. Otherwise, <SAMP>i</SAMP> points to the first element not "less" than <SAMP>value</SAMP>, and <SAMP>j</SAMP> points to the first element greater than value. In the second version, the ordering is defined by the comparison object. Formally, <SAMP>equal_range()</SAMP> returns a sub-range <SAMP>[i, j)</SAMP> such that <SAMP>value</SAMP> can be inserted at any iterator <SAMP>k</SAMP> within the range without violating the ordering. Depending upon the version of the algorithm used, <SAMP>k</SAMP> must satisfy one of the following conditions: </P>
	<P><SAMP>!(k < value) && !(value < k)</SAMP></P>
	<P> or </P>
	<P><SAMP>comp(k,value) == false && comp(value, k) == false</SAMP></P>
	<P>The range <SAMP>[start,finish)</SAMP> is assumed to be sorted. Type <SAMP>T</SAMP> must be LessThanComparable.</P>
	<A NAME="sec5"><H3>Complexity</H3></A>
	<P><SAMP>equal_range()</SAMP> performs at most <SAMP>2 * log(finish - start) + 1</SAMP> comparisons.</P>
	<A NAME="sec6"><H3>Example</H3></A>

	<UL><PRE>//
	// eqlrange.cpp
	//

	#include <algorithm>
	#include <functional>
	#include <iostream>
	#include <vector>



	int main ()
	{
	// Typedef for convenience.
	typedef std::vector<int, std::allocator<int> > vector;

	vector::value_type arr[] = {
	0, 1, 2, 2, 3, 4, 2, 2, 2, 6, 7
	};

	// Set up a vector.
	vector v1 (arr, arr + sizeof arr / sizeof *arr);

	// Try equal_range variants.
	std::pair<vector::iterator, vector::iterator> p1 =
	std::equal_range (v1.begin (), v1.end (), 3);

	std::pair<vector::iterator, vector::iterator> p2 =
	std::equal_range (v1.begin (), v1.end (), 2,
	std::less<vector::value_type> ());

	// Output results.
	std::cout << "\nThe equal range for 3 is: "
	<< "(" << *p1.first << " , "
	<< *p1.second << ")" << std::endl;

	std::cout << "\nThe equal range for 2 is: "
	<< "(" << *p2.first << " , "
	<< *p2.second << ")" << std::endl;

	return 0;
	}


	Program Output
	</PRE></UL>
	<UL><PRE>
	The equal range for 3 is: (3 , 4)

	The equal range for 2 is: (2 , 3)
	</PRE></UL>
	<A NAME="sec7"><H3>See Also</H3></A>
	<P><B><I><A HREF="binary-function.html">binary_function</A></I></B>, <SAMP><A HREF="lower-bound.html">lower_bound()</A></SAMP>, <SAMP><A HREF="upper-bound.html">upper_bound()</A></SAMP></P>
	<A NAME="sec8"><H3>Standards Conformance</H3></A>
	<P><I>ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 25.3.3.3</I></P>

	<BR>
	<HR>
	<A HREF="equal.html"><IMG SRC="images/bprev.gif" WIDTH=20 HEIGHT=21 ALT="Previous file" BORDER=O></A><A HREF="noframes.html"><IMG SRC="images/btop.gif" WIDTH=56 HEIGHT=21 ALT="Top of Document" BORDER=O></A><A HREF="booktoc.html"><IMG SRC="images/btoc.gif" WIDTH=56 HEIGHT=21 ALT="Contents" BORDER=O></A><A HREF="tindex.html"><IMG SRC="images/bindex.gif" WIDTH=56 HEIGHT=21 ALT="Index page" BORDER=O></A><A HREF="equal-to.html"><IMG SRC="images/bnext.gif" WIDTH=20 HEIGHT=21 ALT="Next file" BORDER=O></A>

	<!-- Google Analytics tracking code -->
	<script src="http://www.google-analytics.com/urchin.js" type="text/javascript">
	</script>
	<script type="text/javascript">
	_uacct = "UA-1775151-1";
	urchinTracker();
	</script>
	<!-- end of Google Analytics tracking code -->

	</BODY>
	</HTML>