first commit
This commit is contained in:
Jose Caban
143
extern/stdcxx/4.2.1/doc/stdlibref/count.html
vendored
Normal file
143
extern/stdcxx/4.2.1/doc/stdlibref/count.html
vendored
Normal file
@@ -0,0 +1,143 @@
|
||||
<!--
|
||||
Licensed to the Apache Software Foundation (ASF) under one or more
|
||||
contributor license agreements. See the NOTICE file distributed
|
||||
with this work for additional information regarding copyright
|
||||
ownership. The ASF licenses this file to you under the Apache
|
||||
License, Version 2.0 (the License); you may not use this file
|
||||
except in compliance with the License. You may obtain a copy of
|
||||
the License at
|
||||
|
||||
http://www.apache.org/licenses/LICENSE-2.0
|
||||
|
||||
Unless required by applicable law or agreed to in writing, software
|
||||
distributed under the License is distributed on an "AS IS" BASIS,
|
||||
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
|
||||
implied. See the License for the specific language governing
|
||||
permissions and limitations under the License.
|
||||
|
||||
Copyright 1999-2007 Rogue Wave Software, Inc.
|
||||
-->
|
||||
|
||||
<HTML>
|
||||
<HEAD>
|
||||
<TITLE>count(), count_if()</TITLE>
|
||||
<LINK REL=StyleSheet HREF="../rw.css" TYPE="text/css" TITLE="Apache stdcxx Stylesheet"></HEAD>
|
||||
<BODY BGCOLOR=#FFFFFF>
|
||||
<A HREF="copy.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="cout.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>count(), count_if()</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">Warnings</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 counts the number of elements in a range that satisfy a given condition</P>
|
||||
<A NAME="sec3"><H3>Synopsis</H3></A>
|
||||
|
||||
<PRE>#include <algorithm>
|
||||
|
||||
namespace std {
|
||||
template<class InputIterator, class T>
|
||||
typename iterator_traits<InputIterator>::difference_type
|
||||
count(InputIterator start, InputIterator finish,
|
||||
const T& value);
|
||||
|
||||
template <class InputIterator, class T, class Size>
|
||||
void count(InputIterator start, InputIterator finish,
|
||||
const T& value, Size& n);
|
||||
|
||||
template<class InputIterator, class Predicate>
|
||||
typename iterator_traits<InputIterator>::difference_type
|
||||
count_if(InputIterator start, InputIterator finish,
|
||||
Predicate pred);
|
||||
|
||||
template <class InputIterator, class Predicate, class Size>
|
||||
void count_if(InputIterator start, InputIterator finish,
|
||||
Predicate pred, Size& n);
|
||||
}
|
||||
</PRE>
|
||||
<A NAME="sec4"><H3>Description</H3></A>
|
||||
<BLOCKQUOTE><HR><B>
|
||||
NOTE -- The second versions of the count() and count_if() functions are not part of the C++ Standard, but are included here as extensions for compatibility purposes. See <A HREF="B.html">Appendix B</A> for a complete list of extensions of this implementation.
|
||||
</B><HR></BLOCKQUOTE>
|
||||
<P>The <SAMP>count()</SAMP> algorithm compares <SAMP>value</SAMP> to elements in the sequence defined by iterators <SAMP>start</SAMP> and <SAMP>finish</SAMP>. The first version of <SAMP>count()</SAMP> returns the number of matches. The second version, which is provided for backwards compatibility or as an alternative to the first in case the template <B><I><A HREF="iterator-traits.html">iterator_traits</A></I></B> isn't provided, increments a counting value <SAMP>n</SAMP> each time it finds a match. In other words, <SAMP>count()</SAMP> returns (or adds to <SAMP>n</SAMP>) the number of iterators <SAMP>i</SAMP> in the range <SAMP>[start, finish)</SAMP> for which the following condition holds:</P>
|
||||
<P><SAMP>*i == value</SAMP></P>
|
||||
<P>Type <SAMP>T</SAMP> must be <SAMP>EqualityComparable</SAMP>.</P>
|
||||
<A NAME="sec5"><H3>Complexity</H3></A>
|
||||
<P>The <SAMP><A HREF="count.html">count_if()</A></SAMP> algorithm lets you specify a predicate, and returns the number of times an element in the sequence satisfies the predicate (or increments <SAMP>n</SAMP> that number of times). That is, <SAMP>count_if()</SAMP> returns (or adds to <SAMP>n</SAMP>) the number of iterators <SAMP>i</SAMP> in the range <SAMP>[start, finish)</SAMP> for which the following condition holds: </P>
|
||||
<P><SAMP>pred(*i) == true.</SAMP></P>
|
||||
<P>Both <SAMP>count()</SAMP> and <SAMP><A HREF="count.html">count_if()</A></SAMP> perform exactly <SAMP>finish - start</SAMP> applications of the corresponding predicate.</P>
|
||||
<A NAME="sec6"><H3>Example</H3></A>
|
||||
|
||||
<UL><PRE>//
|
||||
// count.cpp
|
||||
//
|
||||
|
||||
#include <algorithm> // for count, count_if
|
||||
#include <functional> // bind2nd, less
|
||||
#include <iostream> // for cout, endl
|
||||
#include <vector> // for vector
|
||||
|
||||
|
||||
|
||||
int main ()
|
||||
{
|
||||
// Typedef for convenience.
|
||||
typedef std::vector<short, std::allocator<short> > vector;
|
||||
|
||||
const vector::value_type a [] = {
|
||||
1, 2, 3, 4, 5, 5, 7, 8, 9, 10
|
||||
};
|
||||
vector::size_type i = 0, j = 0, k = 0;
|
||||
|
||||
// Set up a vector.
|
||||
const vector v (a + 0, a + 10);
|
||||
|
||||
std::count (v.begin (), v.end (), 5, i); // Count fives
|
||||
std::count (v.begin (), v.end (), 6, j); // Count sixes
|
||||
|
||||
// Count all elements less than 8.
|
||||
std::count_if (v.begin(), v.end(),
|
||||
std::bind2nd(std::less<vector::value_type>(), 8), k);
|
||||
|
||||
std::cout << i << " " << j << " " << k << std::endl;
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
|
||||
Program Output:
|
||||
</PRE></UL>
|
||||
<UL><PRE>2 0 7
|
||||
</PRE></UL>
|
||||
<A NAME="sec7"><H3>Warnings</H3></A>
|
||||
<P>If your compiler does not support partial specialization, the first version of both <SAMP>count()</SAMP> and <SAMP><A HREF="count.html">count_if()</A></SAMP>, the version that returns the count, is not available.</P>
|
||||
<A NAME="sec8"><H3>Standards Conformance</H3></A>
|
||||
<P><I>ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 25.1.6</I></P>
|
||||
|
||||
<BR>
|
||||
<HR>
|
||||
<A HREF="copy.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="cout.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>
|
||||
Reference in New Issue
Block a user