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| <H2>equal_to</H2> |
| <P><B>Library:</B> <A HREF="2-4.html">General utilities</A></P> |
| |
| <PRE><HR><B><I>Does not inherit</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">Interface</A></LI> |
| <LI><A HREF="#sec6">See Also</A></LI> |
| <LI><A HREF="#sec7">Standards Conformance</A></LI> |
| </UL> |
| <A NAME="sec1"><H3>Local Index</H3></A> |
| No Entries |
| <A NAME="sec2"><H3>Summary</H3></A> |
| <P>A binary function object that returns <SAMP>true</SAMP> if its first argument equals its second</P> |
| <A NAME="sec3"><H3>Synopsis</H3></A> |
| |
| <PRE>#include <functional> |
| |
| namespace std { |
| template <class T> |
| struct equal_to; |
| } |
| </PRE> |
| <A NAME="sec4"><H3>Description</H3></A> |
| <P><B><I>equal_to</I></B> is a binary function object. Its <SAMP>operator()</SAMP> returns <SAMP>true</SAMP> if <SAMP>x</SAMP> is equal to <SAMP>y</SAMP>. You can pass an <B><I>equal_to</I></B> object to any algorithm that requires a binary function. For example, the <SAMP><A HREF="find-if.html">find_if()</A></SAMP> algorithm finds the first occurrence of any value from one sequence in another sequence as determined by applying a binary comparison operation. <B><I>equal_to</I></B> would be used in that algorithm in the following manner:</P> |
| |
| <UL><PRE> |
| vector<int> vec1; |
| vector<int> vec2; |
| vector<int>::iterator iter1; |
| . |
| . |
| . |
| iter1 = find_if(vec1.begin(), vec1.end(), |
| vec2.begin(), vec2.end(), <B>equal_to</B><int>()); |
| </PRE></UL> |
| <P>After this call to <SAMP><A HREF="find-if.html">find_if()</A></SAMP>, <SAMP>iter1</SAMP> points to the first element in <SAMP>vec1</SAMP> for which <SAMP>equal_to(vec1[n],vec2[n])</SAMP> returned <SAMP>true</SAMP>; or, if there were no matches, <SAMP>iter1</SAMP> points to <SAMP>vec2.end()</SAMP>.</P> |
| <A NAME="sec5"><H3>Interface</H3></A> |
| |
| <UL><PRE>namespace std { |
| template <class T> |
| struct equal_to : binary_function<T, T, bool> { |
| bool operator()(const T& x, const T& y) const; |
| }; |
| } |
| </PRE></UL> |
| <A NAME="sec6"><H3>See Also</H3></A> |
| <P><B><I><A HREF="binary-function.html">binary_function</A></I></B>, <A HREF="functionobjects.html">Function Objects</A></P> |
| <A NAME="sec7"><H3>Standards Conformance</H3></A> |
| <P><I>ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 20.3.3</I></P> |
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