📄 copy_n.html
字号:
<HTML>
<HEAD>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
<META NAME="Author" CONTENT="Zafir Anjum">
<TITLE>MFC Programmer's SourceBook : STL Programmer's Guide</TITLE>
<META name="description"
content="A freely available implementation
of the C++ Standard Template Library, including
hypertext documentation.">
<META name="keywords"
content="generic programming, STL, standard template library">
</HEAD>
<SCRIPT LANGUAGE="JavaScript"><!--
var adcategory = "cpp";
// -->
</SCRIPT>
<body background="../../fancyhome/back.gif" bgcolor="#FFFFFF" >
<SCRIPT LANGUAGE="JavaScript"><!--
var nfrm = location.href.indexOf("_nfrm_");
var validframes = (top.frames.length > 0 && top.frames['ad'] && top.frames['logo'] );
var random = Math.random();
if( !validframes && nfrm == -1 )
{
var dclkPage = "www.codeguru.com/";
if( self.adcategory )
dclkPage += adcategory;
else
dclkPage += "mfc";
document.write('<nolayer><center>');
document.write('<iframe src="http://ad.doubleclick.net/adi/' + dclkPage + ';ord='
+ random + '" width=470 height=62 marginwidth=0 marginheight=0 hspace=0 vspace=0 '
+ 'frameborder=0 scrolling=no bordercolor="#000000">');
document.write('<a href="http://ad.doubleclick.net/jump/' + dclkPage + ';ord='
+ random + '">');
document.write('<img src="http://ad.doubleclick.net/ad/' + dclkPage + ';ord='
+ random + '" height=60 width=468>' + '</a>');
document.write('</iframe>');
document.write('</center></nolayer>');
document.write('<layer src="http://ad.doubleclick.net/adl/' + dclkPage +
';ord=' + random + '"></layer>');
document.write('<ilayer visibility=hide width=468 height=83></ilayer>');
}
// top.location = "/show.cgi?" + adcategory + "=" + location.pathname;
// -->
</SCRIPT>
<noscript>
<p align="center">
<a href="http://ad.doubleclick.net/jump/www.codeguru.com/cpp;ord=Nupa39FCY34AAHhlPAU">
<img src="http://ad.doubleclick.net/ad/www.codeguru.com/cpp;ord=Nupa39FCY34AAHhlPAU"></a>
</p>
</noscript>
<BR Clear>
<H1>copy_n</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>
<pre>
template <class <A href="InputIterator.html">InputIterator</A>, class Size, class <A href="OutputIterator.html" tppabs="http://www.sgi.com/Technology/STL/OutputIterator.shtml">OutputIterator</A>>
OutputIterator copy_n(InputIterator first, Size count,
OutputIterator result);
</pre>
<h3>Description</h3>
<tt>Copy_n</tt> copies elements from the range <tt>[first, first + n)</tt> to the
range <tt>[result, result + n)</tt>. That is, it performs the assignments
<tt>*result = *first</tt>, <tt>*(result + 1) = *(first + 1)</tt>, and so on.
Generally, for every integer <tt>i</tt> from <tt>0</tt> up to (but not including)
<tt>n</tt>, <tt>copy_n</tt> performs the assignment <tt>*(result + i) = *(first + i)</tt>.
Assignments are performed in forward order, <i>i.e.</i> in order of
increasing <tt>n</tt>. <A href="#1">[1]</A>
<P>
The return value is <tt>result + n</tt>.
<h3>Definition</h3>
Declared in <A href="algo.h">algo.h</A>. The implementation is in
<A href="algobase.h">algobase.h</A>.
<h3>Requirements on types</h3>
<UL>
<LI>
InputIterator is a model of <A href="InputIterator.html">Input Iterator</A>.
<LI>
OutputIterator is a model of <A href="OutputIterator.html">Output Iterator</A>.
<LI>
<tt>Size</tt> is an integral type.
<LI>
InputIterator's value type is convertible to a type in
OutputIterator's set of value types.
</UL>
<h3>Preconditions</h3>
<UL>
<LI>
<tt>n >= 0</tt>.
<LI>
<tt>[first, first + n)</tt> is a valid range.
<LI>
<tt>result</tt> is not an iterator within the range <tt>[first, first + n)</tt>.
<LI>
<tt>[result, result + n)</tt> is a valid range.
</UL>
<h3>Complexity</h3>
Linear. Exactly <tt>n</tt> assignments are performed.
<h3>Example</h3>
<pre>
<A href="Vector.html">vector</A><int> V(5);
<A href="iota.html">iota</A>(V.begin(), V.end(), 1);
<A href="List.html">list</A><int> L(V.size());
copy_n(V.begin(), V.size(), L.begin());
assert(<A href="equal.html">equal</A>(V.begin(), V.end(), L.begin()));
</pre>
<h3>Notes</h3>
<P><A name="1">[1]</A>
<tt>Copy_n</tt> is almost, but not quite, redundant. If <tt>first</tt> is an
<A href="InputIterator.html">input iterator</A>, as opposed to a <A href="ForwardIterator.html" tppabs="http://www.sgi.com/Technology/STL/ForwardIterator.shtml">forward iterator</A>, then the
<tt>copy_n</tt> operation can't be expressed in terms of <tt><A href="copy.html">copy</A></tt>.
<h3>See also</h3>
<tt><A href="copy.html">copy</A></tt>, <tt><A href="copy_backward.html" tppabs="http://www.sgi.com/Technology/STL/copy_backward.shtml">copy_backward</A></tt>
<HR SIZE="6"> <FONT SIZE="-2"> Copyright © 1996 Silicon Graphics, Inc.
<HR>
<TABLE BORDER=0 WIDTH="100%" >
<TR>
<TD WIDTH="33%"><FONT SIZE=-1><A HREF="index.html" >
STL</A></FONT></TD>
<TD WIDTH="33%">
<CENTER><FONT SIZE=-2>© Copyright 1997-1998 CodeGuru</FONT> </CENTER>
</TD>
<TD WIDTH="34%">
<DIV ALIGN=right><FONT SIZE=-1>Contact : <A HREF="mailto:webmaster@codeguru.com">webmaster@codeguru.com</A> </FONT></DIV>
</TD>
</TR>
</TABLE>
<SCRIPT LANGUAGE="JavaScript" ><!--
var adurl = "/cgi-bin/doubleclick.cgi?";
if( self.adcategory )
adurl += adcategory;
else
adurl += "mfc";
if( self.parent.norefreshad )
parent.norefreshad = false;
else if( validframes )
parent.frames['ad'].location = adurl;
if( !validframes && nfrm == -1)
{
var dclkPage = "www.codeguru.com/";
if( self.adcategory )
dclkPage += adcategory;
else
dclkPage += "mfc";
// var random = Math.random();
document.write('<nolayer><center>');
document.write('<iframe src="http://ad.doubleclick.net/adi/' + dclkPage + ';ord='
+ random + '" width=470 height=62 marginwidth=0 marginheight=0 hspace=0 vspace=0 '
+ 'frameborder=0 scrolling=no bordercolor="#000000">');
document.write('<a href="http://ad.doubleclick.net/jump/' + dclkPage + ';ord='
+ random + '">');
document.write('<img src="http://ad.doubleclick.net/ad/' + dclkPage + ';ord='
+ random + '" height=60 width=468>' + '</a>');
document.write('</iframe>');
document.write('</center></nolayer>');
document.write('<layer src="http://ad.doubleclick.net/adl/' + dclkPage +
';ord=' + random + '"></layer>');
document.write('<ilayer visibility=hide width=468 height=83></ilayer>');
}
// -->
</SCRIPT>
<!-- SCRIPT LANGUAGE="JavaScript" SRC="/global/fscript.js">
//
</SCRIPT -->
<noscript>
<p align="center">
<a href="http://ad.doubleclick.net/jump/www.codeguru.com/cpp;ord=Nupa39FCY34AAHhlPAU">
<img src="http://ad.doubleclick.net/ad/www.codeguru.com/cpp;ord=Nupa39FCY34AAHhlPAU"></a>
</p>
</noscript>
</BODY>
</HTML>
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -